Great. A promising dev, ruined with inevitable dumbed down consoletardism.
Maybe not this game, but the next and the next until EA buys them and fires everyone.
Well, they said they wanted to make Baldur's Gate, and that's what happened with the last devs who made Baldur's Gate, so history supports your argument.
Heavy makes you move slower and aldori only get the damage resistance part of armor training. But basically yes if you have bad dex heavy is good and if you have good dex medium or light is better and with great dex none is actually best once you get +8 bracers of armor. 30 dex = +10 + 8 bracers= 18. full plate +5 = 14 + 1 = 15. But with armor training and mithral full plate that can change to actually being better since you can get 6 or 7 from dex and come out 2 better. But no armor lets you take a level of monk and still come out slightly better. But there are also robes that can give +5 dodge to bring none ahead more in total
In the end heavy and none can be, in theory, within 1 or 2 of each other. But none will still come out ahead because it will have much much better touch ac (like 10 or more better) and touch ac is very very important.
Good analysis, but I think Flat-Footed is still important on your primary tank at least, so you don't get 1-rounded. Heavy Armor will give you better Flat-Footed AC at least.
If you want a very good dodge tank you should get uncanny dodge through 1 of the 3 ways, i.e R4, Barb2 or Arch2. Since R4 give you an options for -4 AC or -4 tohit debuff and also the 2d sneak attack is very easy to make happen on your tank via flanking. Most OP tanking builds probably want R4. Rules wise getting Uncanny twice should give Improved uncanny and protect against SA, but that does not seem to actually happen in game, so you would need to save edit that in to adhere to rules, but in that case a Arch2/R4 with whatever else could work ok, not sure if its better than simply taking perserve organs from Viv. You can't do barb with 1 level of monk, so its generally a no-go for OP builds meant to no-armor tank.
So basically no armor tanking is optimally no question better, but will almost certainly take a lot of multiclassing. If you are going straight up one or two classes and not being complex then you may need to deal with trade offs like being flat footed vs better touch ac. But at the extremes no armor is strictly better. Higher total AC and much higher touch AC and no flat footed anyway.
For example here is a build:
Kensai 7, KF 4, Viv 3, SF1, Pal2, du3. This would go no armor and use lawful good monk robes and never be flat footed. This is a level 20 build since its my tank for my duo but you can just not have duelist for a level 17 build in a 6 man. This is a tank with 5d8 sneak attack (with sai in flurry of blows +1 attack, open hand) and +2 secondary attacks when feral mutagened and you can add two elements to your weapon 4 times for 7 minutes each. Go int 15+1 and cha 16 or 18 and dex 18(+4) with 10 wis. Halfling or musetouched aasimar. This can also be a skill monkey for all dex stuff and perception and UMD. It has room to be persusaion/dazzling display as well if you lose one of the other skills and you can switch KF to thug. And should have 20+ in every save. Wep finesse damage from rogue for sai, don't bother trying to enhance the feral mutagen attacks with strength or slashing grace, since for halfing (the probably best choice) with reduce person that will be low anyway, just proc SA and precise strike and +3 damage arcane strike on it.
Is that a lot of classes? yes its a stupid amount but its imminently doable and is 16 BAB and has Mirror Image/blur/displacement/shield. I am not sure if MI is needed as castable on a tank, there may be neckalce that gives you MI called Gyronna's amulet but losing Kensai for something else actually does very little anyway.
I use this with my Sylvan sorc/feyspeaker mystic theurge and use the level 12 (at max) smilodon to proc flanking and do extra damage.