This game is messed up. Sometimes you turn a corner and get instantly lasered to death. Other times, the AI is so dumb, you can literally walk circles around them. The gunplay is objectively wack. The tiny inventory forces you to hoard your loot on the floor like your sword collection in Morrowind. But I can't get enough. Exploration is always rewarded since items/money/ammo are just scarce enough to feel important. The scope of the game is sane and doesn't bog you down with tons of pointless side quests (think Fallout 1 vs. Skyrim). And it's all bursting with solo-dev charm and pre-quest markers game design.
Wasteland 3 is maybe an average to above average one of these games. You roam the wasteland, read dialogue, find loot, go on fetch quests, put your tanks up front and shooters behind cover in the back. You've probably played games like it before. The co-op puts it above and beyond though. If you're looking for a "truly" co-op CRPG, your options are essentially the Divinity:OS games and this. Older similar games generally play like Player 1 and Player 1's Helper(s). It's a huge amount of fun playing through offline story based tactical RPGs like this with my partner, and for whatever reason there's so, so few of them like it. The scarcity in the co-op genre puts it among the top of the genre by default.
Here's a mystery: why do almost no ARPGs have controller support? ARPGs of old have taken a toll on my wrist and I can only play with a controller now, so Grim Dawn is my only real option for a game with loads of content and a big variety of builds. And it's fine. Grim Dawn is not a very unique game. It doesn't have a big personality. It doesn't have great writing or classic voice acting. It doesn't have epic set piece bosses and cut scenes. It has a standard gameplay loop and better-than-mediocre combat. It does has a great deal of character customization, which is its strongest point. Maybe it's not a fair comparison based on budgets, but Grim Dawn is Path of Exile but at least a little worse in basically every way but one: I can play it with a controller on PC. For that reason, I play Grim Dawn.