I used to play a bunch Japanese games and VN, and I liked Illusion games before they changed. In old times, few year ago, Japanese games and VN were much better than lot of western ones I played. I didn't play a lot, just a few, and in many case I much prefer (even today) the Japanese because they are often perfectionist and the quality of pictures/videos is usually much better than not Japanese. Also, our stories often are situated around home life or schools, so, these can also be appealing. I seen some VN here in LC and some are decent but I feel some need more work, but to be honest I like visual and also decent story, not just fucking, which a lot I seen. Myself, I like loli VN so, this is also something that I prefer to see and these days there are get less of them round.
which do you prefer?
I think It'd be japanese ones, but I never played much because of the language barrier. The universal language for the Ren'Py game here are english, even if the dev speaks russian, spanish or whatever, there'll always be a english version. As for the japanese ones, it's usually japanese only.

Some of them don't even let you run them normaly, only with the computer is set to Japan or something like that...
I myself prefer the anime style, and japanese AVNs has a lot more fetishes than what we find here. I go to VNDB and see many games with tags that I like that I won't play.

I didn't play much Illusion. I remember play Rapelay just because of the controversy, Sexy Beach, SchoolMate ,
@Home Mate, Jinkou Gakuen, and some Jinkou Shoujo, don't remember which one. I also their most popular ones nowadays played Honey Select and Koikatsu. I liked their games but when I played them it's was running them because of the unnoficial english patches and such. Hahaha
Really sad that they closed down. They were pioneers on non-VN porn games, and they were really good on that.

I also like schools and such, as I always liked some slice of life settings. I don't need a complex plot, just some nice dialogue and hot scenes.
Sadly the future for loli isn't very bright. More and more companies keeps banning it. I'm afraid of the best ones will always be what we already have...