For a hentai RPG, I've been recommending "MaiDenSnow Eve" to people lately.
It's a bit more of a roguelike than an typical RPG, but I enjoyed it a lot. The h-content (and core gameplay) is based around actual combat and defeat, rather than hunting for CGs which could otherwise be found within a 30 second google search. Which is a big plus point in my opinion. Getting defeated doesn't result in a game over and loading a save, like most games, either. You can carry on, simply more corrupted than before. Has a partial English translation built in.
Gotta throw my hat in for Dragon Age because, well, consummation of my life, basically.
Then there's a seconding for Dragon Warrior/Quest and Final Fantasy and Legend of the Dragoon.
Baldur's Gate
Planescape: Torment
Fallout
Neverwinter Nights
Mass Effect
King's Quest (if you like puzzlers)
Dragon Age(the first) and Chrono Trigger have been mentioned already, so I'm out of ideas
Only other thing aside from those I can recommend is pen and paper RPGs with other people. Those can be great too if you're with good people to play them with
Kingdom hearts, persona 3 and 4, elderscrolls:skyrim, dragon age origin and inquisition, digimon cyber sleuth, chrono trigger , chrono cross, pokemon, final fantasy and mass effect 1-3.
it's my favourite RPG, well maybe not so much 'rpg', but 'adventure-rpg'? Anyhow, my favourite game of all time, check it out, already mentioned it in the game thread.
Definitely get it, while it doesn't quite live up to what I loved about the original, Inquisition certainly beats the pants off of the second dragon age game.
Inquisition ate my life. It was a second job. I would get home from work, plug away at murdering demons for a bit, go to sleep, and sneak in an hour before work. I was putting in 40 hours a week with it. That's not a thing I do often, so I'd have to recommend it.