2nd D3 was my 1st Dungeon Crawler.
I can't compare to previous Diablo games but as someone who started this Genre with D3 I am satisfied with the game (Ok a few tweaks on certain things would top it off) but I read a lot of comparison to Torchlight 2 so it made me try the game out, and after spending 6 hours or so with the game I'm a bit confused by why people reckon it's a better game.
Torchlight fortunately (Coming from someone who grew up with a lot of RPGs) has the traditional Skill Points/Stat Points.. but at a cost.. it is a complete mess, sorry but someone who uses magic should heavily stack on a magic stat not evenly spread about to get "Higher Crit/Dodge" etc as that is taking the point away from going to a magic class, but the skill points are useful if done correctly.. but then D3 auto stat upgrades are toned to each class. Again a Wizard will get 3 int points, 2 Vit points 1 Str/Dex.. that is pretty much a good stat set as it benefits the strength of the character being used. Now the skill trees, we all love a good skill tree.. but with Torchlight I found myself holding the Left Click button 95% of the time and not caring about the skill I unlocked or upgraded as there seemed to be too many options in each tree, 1 tree tonnes of options good, 3 trees few options on which way to go is good, 3 trees tonnes of options.. seems too much. At least in Diablo whatever skill set up you do go with (Ok a problem being most classes have a strong skill build that everyone uses) the skill are all useful to the build.
Now Graphics.. not a problem for me usually but I couldn't grasp the cartoony feel of TII it seemed like the graphics wasn't built for the style of the game, all well and good being colourful and what not but it seemed out of place.
The story in D3 is very linear but the areas are well designed and play very smoothly, TII seemed very clustered and awkward to traverse. I couldn't grasp any story of TII but maybe that is the graphics and clustered areas causing me to feel unwanting to follow the story.
I'm not saying D3 is perfect and I agree with many posters about a Skill Tree (MUST be done well) maybe a slight say on Stat points but not too concerned as I think they spread them well for each class. Also more areas and maybe a full on Dungeon Crawl where it's a non stop descent into madness instead of having to find a dungeon here or there with 2 to 3 levels at most. But I am saying I heavily preferred D3 to TII.
People will disagree with me but this is my view, I'm more than open to try other games in the same genre. maybe not much older games but definitely not tied to just this.
Edit: I have read a few forums on here and have seen the reactions of some of the members, if someone wants to reply please be mature about it and not heavily biased towards one or the other.