We clearly played this game very differently! Which speaks to it being well-designed, I guess.
That's pretty interesting. I wouldn't have put Archon or any of the full tanks in the upper half of the list, even for max difficulty. They all drop the party's offense pretty hard, and I feel like the amount of support they provide is only necessary if you drop the party's offense by bringing them. It felt like lower damage teams ended up having to let some elites go early on in Entropy V, which delayed a run snowballing a bit, but prioritizing damage lets me pretty consistently kill every elite and even a planet 1 moon if it shows up.
Early elites fleeing was definitely a problem on several of my runs, although I was usually able to stop it with careful planning/application of Stuns, but even when they still got away, losing out on 5 DNA or whatever isn't a big deal. That said, a planet 1 moon is trivial with a tank; they can just stand on the front row and soak all of the bomb bots. It's a long fight, but an easy one to end at full health and shields. As long as I started with a high damage unit like a Spectre or a Marksman, I never felt short on offense.
I haven't played recently enough to give my own tier list, but Paragon/Spectre/Empath was my preferred start. I used the Spectre progeny with the AoE at level 4, and the Empath progeny with the strength aura at level 1. Paragon provided more than enough tanking, especially with some shield defense stacking, without sacrificing much damage and also staggering extremely well with a little gear. Empath is good enough at restoring shields, has a top-tier bond bonus, great fury ability, and has an insane combo attack with Spectre that will instantly wipe out anything short of an elite (and also some elites). The AoE, stun, combo, and better shield defense card on Spectre are why I preferred her to Marksman.
I didn't play enough games to unlock most of the progeny (I think I only had two losses, both because I was trying to make Aegis and Enforcer have a baby on Entropy IV so I could unlock the last class before my final run, and they're a terrible starting duo), although I did forget to take into account the Empath's Fury ability, which probably bumps her up to a C for me.
And you make a good point about the Spectre's card-- it's very good. That said, the Marksman's card is pretty similar and almost as good. My favourite use case for both is using one of them before a Behemoth fight and then using it again on the ship so that you can do a single fight on the next planet with stacking bonuses-- very fun if you can immediately ram yourself into an elite. I didn't really take card selection into account when doing my rankings, mostly because I couldn't remember the cards. I feel like card selection should be a secondary concern, other than to note that the Guardian's are bad. I usually spent 2 points/campfire doing +5 permanent max shields to everyone and the final 3 trying to make hearts anyway, unless I knew I was going to start the next day by doing something difficult.
AoE is something I prioritized heavily, since it's really easy to just nuke all the chaff before they can act with Siphon Stab + 2 AoEs. Stun is also incredible, since you can just stun bigger enemies once you can't stagger them anymore, then proceed to stagger them all over again the next turn. You can literally never have too much of it, and you're kind of crazy to put a character with a stun at the bottom of the list.
Enh. I like have a single AoE staggerer, but tend not to like AoE moves otherwise. I'd much rather remove problems one at a time; I rarely used them.
And I like having a single stun in the party for emergencies, but I've had parties with 3 stuns and felt like it was too many. Not to mention how often stun immunity starts showing up on higher Entropy levels, or that one jerk Behemoth who actively punishes it. To me Stun feels like a crutch. I'd rather have sustain than be in a position where I'm trying to kill an enemy before it can kill me. I'm usually able to hang out in most fights indefinitely; I finished my final Entropy V run at max health and shields for everyone. I guess it's fun to use stuns to skip the last phase of the final battle to speed it up a bit.
I never felt like Marksman being able to move around to a bunch of spots on the timeline was very valuable, so he was just pretty high ranged damage to me. Honestly he feels like one of the most narrow characters in the game to me.
I couldn't disagree more. I feel like he's super flexible. He can hit anyone, go at any speed from instant to dead last, stagger, destroy armor, debuff enemy shields, turn off enemy crits, etc. Being able to hop all over the turn chart is huge, because you can mix him in just where you need to make something happen, usually in an effort to make the Archon's shield heal land at the best possible moment (sometimes assisted by shutting of an enemy crit so that Archon doesn't take extra damage while doing so).
Guardian is the worst character in the game IMO. Aside from the reasons you listed, he's actually just really bad at tanking because he doesn't have any free way to redirect/mitigate damage like every other tank. On top of that, his gear requirements don't overlap with any other character in the game, so you probably won't have any of it starred unless you're starting a run with him, which you won't want to do because he's worse than the other tanks.
No argument here, expect that I feel like every party needs a tank and Guardian is one of only 3 dedicated tanks, so being the worst tank still makes them middling at worst. And even if you have the bad shield item that grants health and health damage resistance demoted, chances are good you'll see one at some point that you can shove their way. Same with an implant that steals health on hit (once you can have your Guardian start every turn with a healing flurry they are essentially unkillable). Also, Stronghold is just stupidly good, and with good Fury income you can almost use it every other turn. I actually like picking up a late Guardian as an offtank to make a nigh unkillable party; your damage suffers for having two tanks, but splitting the damage between two tanks takes the pressure off both, and you can ~blank every high damage enemy turn.