She has high HP, Moderate Eva, and no armor. As a tank, you'll find she melts considerably faster than similar G&K units.

Your primary armored DPS that isn't a Manticore. In most cases, a Manticore is scarier, but these guys have consistent output and are also armored. And unlike Manticores, you get all 5. You can think of them as armored Jaegers that do better vs high HP enemies and same-ish or worse vs. lower HP enemies.

The big thing about them is their skills. They get bonus damage based on how much max HP a target has, and they can drive their own crit rate up as they keep firing.

They do however, apparently have defective targeting systems, so you NEED something else like a Jaeger to provide range, because otherwise they're kind of not going to spot anything to shoot.

They have an HP shield, and at 4 stars can reduce damage taken for both themselves and allies in the same row. What's not to like? Surprisingly good (61) Evasion at Max, and good Armor (more than a typical SG), and honestly their main issue is relatively low damage and being melee. Which is not really a huge issue for tanks on the front row. Aside from that, theyre basically mostly SGs that beat things with sticks.

Do note that unlike SGs, you cant easily raise their stats with things like formation buffs, fairies and the like.

Yeah, she's not the worst unit, but she's a 2-star (so good luck finishing her), and she's not exactly exceptional. Most pros and criticisms of the Guard still apply. The most common use for her is stacking her shields to tank AoE shots (like Typhon lasers), but otherwise, ehhh.

Unlike the basic Dragoon, this one has an infinite (until shot at) duration shield that replenishes itself at regular intervals. She also has higher stats than the basic version, and the 2nd skill reduces enemy stats.

Basically, if your enemies ignore Armor making AEGIS unsuitable for your frontline, these might work out better. SWAP Rippers are broken, but sometimes these will last longer depending on the specific fight you're gearing up for.

The SWAP Striker has higher offensive stats, better multipliers, and notably higher accuracy than the base version, so it can actually hit things. The main downside to this is it costs 6 instead of 4 to put into your echelon.

Same skill 1, way better skill 2. The really big thing is the shields will absolutely stop the hit that breaks them, so they can take a Goliath to the face and be absolutely fine as long as their shields were up at the time. Also, you get damage reduction for having more units left. The main thing to note about them is they lose their offensive stats (considerably worse RoF, slightly worse Firepower) in exchange for this tankiness, so you'd better have the rest of your echelon be tanky.

The most ridiculous SF tank in the game. She doesn't have Armor, but she has high Evasion, and her second skill works off your echelon setting. In defense mode, every time she loses a link OR her main skill activates, she gets a 9999 power distortion barrier that lasts for a few seconds, meaning that no matter what, she's going to buy you some time. In other modes, it becomes an attack buff that contributes a bit to DPS. And that's her passive. For her active, it triggers her passive and defense mode gives her a considerable 120% Evasion boost, on top of the barrier. In other modes she gets an attack boost that stacks multiplicatively with her passive.

If an SF team needs something ridiculous tanked and you absolutely need to buy time, she is currently the last word in.

Almost across the board, it's an improvement for the Vespid. However, its a pain to get a full formation of them because its a 2 star base unit, and as a DPS unit you want it at full stacks. Also, it's not really significantly better than stuff like Jaegers and Strikers. They're not useless, but there are just much better SF units to spend effort and slot points on.