My favorite specific dildo is the VixSkin Tex. In general, I like my dildos to be curved to hit the G-spot, with either a flared base or some kind of handle. As for realistic vs. not, I like both in different ways.
I like realistic dildos. I'm bi but haven't been with anyone but my wife since we got serious about each other. Haven't seen anyone else's real penis at close range in about 15 years. For me, a dildo is a substitute for the real thing and I like it as realistic as possible. I use dildos both orally and anally. I'm the receiver in both cases; my wife doesn't like being on the receiving end of dildos at all, though she does enjoy strapping on.
For oral, I like Cyberskin. It's the most skin-like I've experienced so far. For pegging, I like Vixskin. Vamp's Softskin is also pretty good and Tantus O2 as well.
I don't really care about suction cups since I almost never use dildos solo. My favorite mounting system (if that's what you call it) is the base of the Vamp Elvis. It's secure and it leaves the "balls" completely outside the harness, which is a great sensation. The mounting system for Vixskin GoodFella is similar, but not quite as good, IMO (but the Goodfella is much better dildo).