Some explanations of the ones which best fit you:
Powder - Has tiles, no classes (deity choice ends up a bit class-y, but you can change frequently mid-game) and lots and lots of randomness. Very easy to get into and quick to play.
ToME4 - Has tiles, great interface. Has classes, but there is a lot of customisation within class progression - it's not linear. It has a lot of random items, but you might find some of the dungeons a bit samey between multiple playthroughs. The game doesn't have a good wiki, entirely because all of the explanations are already in the game in the form of tooltips. Really easy to get into, but also very complex when you get into the depths of things.
Brogue - Has a tiles version, no classes, lots of randomness. Generally considered the best "designed" roguelike in terms of balancing. Lots of interesting features and enemies.
There are no games with a good randomised overworld, with perhaps Dwarf Fortress as an exception.