I found Great Troubles difficult to enjoy because of how often the MC goes on and on about Samantha and how pretty she is yada yada. If i'm playing an M/M, i don't want the character I'm playing as to go on about how straight he is. Personal taste, obviously, but I thought it was pertinant to mention.
Blackgate *is* pretty exceptional, especially in terms of storytelling for the genre.
I'll write a list here, but for brevity's sake, i'm going to avoid listing games you can find on these forums or that were mentioned above. You may also note that I'm not listing any furry games. That said, I will include those in the list if requested.
Other games you may find some interest in;
See No Evil; this is really good, but bara, so if you're not into guys with a bit of chub or chest hair...
Black Grimoire is great, especially for an RPGMaker game, but you need a visual novel reader type program to translate it from JP to ENG. This is also bara, but muscly rather than hair or chub.
The End of Dreams is similar to Black Grimoire, but I preferred BG. That's just personal taste though, so feel free to give it a try.
Sugar Shooter and sequels are also decent bara games, but they're bullet hells, and getting the full sex scenes requires a stellar performance, so if you're just looking to get off, find something less difficult.
Janken Strip is a simple but enjoyable little game. It's only good for half an hour's entertainment, but that could be long enough to get off.
The last game that comes to mind that isn't a VN is Super Health Club. This is alright. The art is pretty good, but the gameplay could be more involved, IMHO.
If we include VNs the list expands considerably but I'll exclude anything you need a VN reader program to translate for you.
Anything by Nitro+ is fantastic and you can always find an english patch. Of these, Dramatical Murder, Togainu no Chi, Sweet Pool and Lamento: Beyond the Void are particularly good. Be warned: with the exception of DM, N+ games are uniformly either violent or disturbing or both. Ranked from safest to most disturbing; DM, L:BtV, TnC and finally SP. If you're at all squeamish, try them in this order.
The Black Monkey games I've played thus far, Sleepover and Bacchikoi are both very good. I love their art, in particular.
Coming Out on Top is pretty good, but I found the main menu music to be so bad that it discouraged me from playing the game for fear that I would have to listen to whole seconds of it.
No, Thank You!! is also pretty good, but it takes a bit to really understand why the MC is the way he is, and his character may be off-putting to some.
Starfighter Eclipse has excellent art, but most of the sex scenes are just a single picture. I'm not sure why that is, but it may have to do with the IP's origin as a webcomic.
Requiesence is reasonably good, but not excellent. I do find the MC to be quite easy on the eyes, however.
Managed to forget Silver Chaos. It's roughly similar to Requiesence in quality, but has more paths. It's drawn in an older yaoi-esque style, so idk if that'd appeal or not.