The BG2 magic system is still richer and more engaging. Loads of stuff there.
As to the core gameplay, it's six of one, half-dozen of the other. DotAheads will prefer BG2 because it's more DotAlike, for example you can learn to cheese the AI in ways Pillars doesn't let you because of engagement.
Content is key though, and there BG2 is head and shoulders above Pillars, even with the WMs.
Systems-wise, other than magic, BG2 is far inferior in almost every way.
Not true I played tons of Dota and as much RTS (sue me that's what you do in 3rd world countries).
While it's true IE engine has a lot of these RTS functions, because well it was built upon a RTS engine, just having a loose-form combat with RTS "tactics" (not even tactics more like minute micro) such as cycling healthbars, kiting or focus fire doesn't make it interesting by itself. IE games (obviously by design) lack all intricate combat aspects of a proper RTS, such as true counter-plays (rock-paper-scissors), macromanagement, build orders, combat tactics and all else. In the end if that's all you focus what you are left is a degenerate subRTS combat with only unique spells going for it.
I don't play AoE2 because I like kiting a boar to my settlement with 6 villagers with bows, that's just something you do for efficiency that's part of a general, greater concept of macro and micro management to build up an advantage. That layer doesn't exist in IE games and it's what you do if you are playing with anything but with a mage, there has to exists something more to it, which there is.
Similarly all arguments about dota or any other similar goes out the window when you play such games, things like kiting in a game like dota is bare minimum mechanical ability to play the game, the game itself is about teamplay and mindgames not kiting someone around. Having such mechanics that are mere basis of a multiplayer game as core challenge against AI is an insult to everyone's intelligence.
What these type of games offer that RTS or Dota-like games don't offer is complex character building, exploration, roleplaying, writing and narrative. If you are playing IE games because you like to this type of minute micro plays you are playing the wrong genre. BG2 isn't good because cheesing AI with a fighter makes for a good system, it's good because it offers unparalled amount of good content.
It's important to focus on what makes these type of RPGs good, such as character builds, diverse encounters, rewarding exploration and entertaining writing instead of creating a cargo cult around basic RTS/Dota mechanics.