All three games are underwhelming.
I once had a argument with a silly person who thought Arcania is worth playing. During that argument I said that in my opinion you can split RPGs in three categories, those that have main focus on combat, storytelling or exploration. My point was that since Arcania is shit in all three departments what exactly is point of playing it.
Now lets see how these three games stand in those categories.
COMBAT:
DOS is a clear winner here and its not even a competition. While there are grindy moments overall the combat is fun, there is an actual diversity in enemy encounters and tactics you need to employ in order to win.
W2 is a mix bag. I played lots of tactical games with better combat but also with worse. While I would like more options to use while in fight I still find present mechanics overall acceptable. Problem on the other hand is enemy encounter design which features few nice combat scenarios but in most cases its just simply uninspired. This is connected with world design which is mostly bunch of corridors which greatly limits tactical options.
PoE combat is just shit. Both mechanical wise and encounter design wise. Biggest problem is that its a game where majority of time is focused on combat, so having such a mess from people who has huge amount of experience working on RTwP combat is inexcusable.
STORYTELLING:
PoE is the winner here but seeing the competition its not really an achievement. I found the entirety of PoE writing just mediocre. The main story line just like side quests and companions jump from interesting to bland and boring. There is little dialog options based on your character choices and even when you get one its mostly just cosmetic. While I would rate writing better then your average RPG I expected much more from Obsidian.
W2, a game for which official Codex review says "The writing ranges from good to great". Well in my experience the writing ranges from good to Fallout 3 level of derp. While W2 has some interesting characters, plot points and side quests I found myself way too many times wondering "who the fuck wrote this shit". When my memories of the game writing is mostly of me facepalming its a not a good sign.
DOS, honestly I cant really say much here because I forgot pretty much every bit of story and characters fromr the game. Overall writing is just serviceable and not memorable in a either good or a bad way.
EXPLORATION:
DOS is also a clear winner in this category. The point of exploration is to find interesting enemies, items and storylines. In DOS there is lots of secret places, interesting non mandatory combat encounters and decent loot system. All this makes exploration of the world both interesting and rewarding even if there are certain areas which are rather a chore.
W2 is not much better then PoE in this regard and it actually manages to be worse in some ways. One of the biggest problem of W2 is corridor based world design, which not only limits combat but also exploration. Only thing of value you can find while exploring are some secrets but they are underwhelming to say atleast. In Fallouts finding a locked chest usually means you will get something useful, in W2 you will probably get few bullets and random junk no matter how well defended or hard to get that container is. Also nothing beats wasting time opening chests that hold nothing but junk, first choose a char to disarm an alarm, then other one to remove a trap and then third one to unlock the chest and all you get is shit. Doesnt help that unlike Fallout chests are few in between, in W2 they are everywhere probably to make those skills useful, too bad there is nothing useful inside them.
PoE, there is no point of exploration since there is no interesting enemy encounters and enemies give little xp while loot is horribly bland but then again there is some nice vistas to look at, thats something right.
CONCLUSION:
DOS has a good combat and in most areas good feeling of exploration but is underwhelming in story/quest design/writing department.
W2, simply a mediocre game which is not really good at anything.
PoE, an action heavy game that has horrible combat, game featuring large open spaces for exploration but with nothing worth exploring for and on top of that a mediocre writing from company famed for great writing.