Hello, and firstly I would like to say, although it should be obvious, that these are my own opinions and analysis of each of the Warframe's abilities. It's perfectly fine to disagree as this is just my own opinion. Also, please note that the listed frames in each tier is just alphabetical and doesn't mean one is better than the other.
Corpus and Grineer defence are similar, Volt is the only frame I would rate differently for each, so no point in seperating these out yet.
Tier 1 Corpus/Grineer: Highly Desirable, some of the best options for Corpus/Grineer Defence:
Banshee - Her 1 and 2 skills is why she earns a slot here, although in less organised teams and pubs she may have diminished effect, as if allies don't target the weak points created, her 2 does not help.
Excalibur - Has a very strong ultimate with good range and armour ignoring damage at max rank, but with the release of Nova, his ult is now comparitably weaker. His 2 is also very useful as an alternate to Vauban's bastille which provides strong reliable AoE cc. Like Vauban, he can be very effective at saving the pod when it's swarmed. Borderline t2 with Nova release.
Frost - Snowglobe earns frost a slot here, and he can keep it up almost indefinitely just with streamline, both continuity mods and energy siphons. Can use his 1 or 4 to protect pod in a tight spot as it freezes enemies, but a vauban's bastille is preferred. His globe is the cornerstone of any Corpus or Grineer defence and he is almost always required. He lets more fragile frames become viable as they are able to negate most damage by staying in the globe instead of facetanking it.
Nova - Her ultimate earns her a spot here, and has replaced several t1 frames on release. It slows 50%, doubles damage on target and as we all know, can have incredible chain damage. It also has an amazing cast range of about 37m with maxed stretch mod. Very fragile so fully reliant on Frost for protection.
Nyx - Nyx's 1 and 3 make her an exceptional defender as she makes opponents fight each other - this never falls off, as they get higher and higher, they'll do more damage to each other. In less organised teams and pubs she may have diminished effect, however, as her controlled enemies can still be targeted by Tenno.
Vauban - Vauban has some of the best skills in the game. His 1 offers very good damage against corpus but does fall off as you go higher up... but Bastille pairs exceptionally well with frost's Snowglobe, making a team very hard to overrun. His ult can also be handy with AoE weapons such as the Ogris or Torrid, but can disrupt other Tenno as well so use carefully. Very fragile so fully reliant on Frost for protection.
Tier 2 Corpus/Grineer: Solid contribution, but there may be better options:
Rhino - A jack of all trades but the king of none, Rhino is able to protect the pod when swarmed, lay down respectable AoE damage and provide a damage boost to his team. He can also revive people in tight spots with iron skin without being knocked down. Probably one of the safest picks for random games as you can play almost any role as him, but in an organised team there are better choices.
Sayrn - Her ultimate ignores armour and does very good damage, like previously a definite tier 1 but with Nova's release she has been outdone and is now in tier 2. Her 4's range is only 10m (15m with stretch) but can damage through objects.
Volt - Yes, he has electric abilities that should make him strong against Corpus, but his 3 only provides an extra 50% of damage only when shooting through the shield, which is outdone by Rhino's, Nova's and Banshee's damage boosting skill, and his ultimate is outdone by armour ignoring ults later on such as Nova, Excal and Sayrn's. Against Grineer, he would be in tier 3 but he's here due to Corpus.
Tier 3 Corpus/Grineer: Questionable contribution, there are probably better options:
Ash - Borderline tier 2 for corpus, he provides strong damage with 1 and 4 and can revive people if they get caught out with invisibility. However, there are almost always some nicer picks due to the delay on the ult and single target damage with 1.
Ember - Fantastic AoE fire damage, but most of it does not ignore armour and will eventually lose out to armour ignoring AoE damage of other frames.
Loki - His decoy will die almost instantly later on and his ult could save the pod in a pinch, but there are better skills for this. He is also fragile. One good point is he can go invisible to revive people who are caught out, but there are usually better choices than Loki.
Mag - Her skills are okay but usually just weaker versions of other frame's skills. Her 3 functions like a weak version of Nyx's abilities and her ult does not ignore armour so will fall off quickly.
Trinity - Her ult can be very handy to heal your sentinels! But aside from that, she doesn't bring much damage or CC, and currently healing isn't as effective as it could be due to using Frost's globe and Vauban's bastille to prevent damage instead of facetanking it.
Tier 1 Infested: Highly Desirable, strong picks for Infested Defence:
Banshee - Ancient infested become pretty tanky as you get higher and higher and her 500% damage boost can make short work of them. She can spam 1 to defend the pod in a pinch, but usually Vauban's bastille is a far superior choice.
Nova - Again, her ult really makes her stand out for infested, with it's giant range with stretch, 50% slow, x2 damage boost to everyone it hits and the chain explosion... on release, knocked out some other frames from tier 1.
Nyx - She shines here... she can use 1 to control a toxic ancient in the middle of a crowd to damage everything next to it or a healer to heal all her allies and the pod. She also still has her 3, which has a massive range with stretch and doesn't ever really fall off.
Vauban - Bastille is an incredible skill for Infested defence, they rely on getting in melee range to damage the pod and Bastille levitates not only anyone who is in the area at the start, but also anyone who enters it... placing it above other similar skills such as Rhino's ult.
Tier 2 Infested: Solid contribution, but there may be better options:
Ash - His ultimate now does 3000 damage instead of 1000 to all types of light infested and Ash can use 1 to burst that one ancient that needs to die, NOW. I'd still prefer to take a Nova over him due to the delay of ult on all targets, but it's unarguable that he can contribute a little more here than the other types of defence.
Ember - Her fire damage does damage infested more, making her stronger for Infested... but it doesn't ignore armour and will fall off eventually, disallowing her from entering tier 1.
Excalibur - He has a powerful ult and good cc... but with Nova and Vauban as options, there's no real reason to choose him anymore.
Rhino - Still a jack of all trades, he is useful but there are still other frames that can do each individual part better than him. Probably one of the safest picks for random games as you can play almost any role as him, but in an organised team there are better choices.
Sayrn - Her ult functions a little better on Infested as it does suffer from a small range of 10m (15m with stretch) as they swarm the pod more instead of hanging back and shooting it. She can also make a decoy which can be useful sometimes... but with Nova, she's sadly been moved out of t1.
Tier 3 Infested: Questionable contribution, there are probably better options:
Frost - Frost does not help at all for infested defence in comparison to other frames. His bubble does provide a slow to infested inside it, but it also hinders any allies from shooting into it and his ult does not ignore armour and the cc is outdone by Vauban's.
Loki - His decoy can be useful if placed in a spot that the infested are still aggro'ed to but can't reach. However I still feel there are nicer options due to better cc such as nyx and vauban around.
Mag - Even less contribution than the other two types due to infested having no shields and not shooting any bullets...
Trinity - Even less contribution to infested defence than the other two types... a nyx can use her 1 on an ancient healer to heal all her allies instead of using a trinity. Furthermore, your sentiels don't get targeted by Infested.
Volt - Electric damage does next to nothing to Ancient infested... a definite t3 frame for infested defence.