I've played:

Saya no Uta
Umineko no Naku Koro ni
Utawarerumono
Fate/Stay Night
Chaos Head ( halfway through, lost interest)
Ever17

Ever 17 is awesome, you should definitely pick that up. It is among the top visual novels for sure. Be very careful of spoilers though, you should just dive right in instead . It is officially translated to English, so it doesn't need a patch.

Saya no Uta is great too.. Utawarerumono was decent. Didn't like Chaos Head that much.
They all have English patches.

Umineko no Naku Koro ni is very good ( already made a thread about it ). The art is "original" but if you get past that it is definitely one of the best VNs that is translated to English.

I've played a few more but I can't remember their names at the moment so I doubt they were that good.