Only had Sonic 1, 2, Knuckles and 3D Blast (The latter which while universally hated wasn't all that bad.). Played 3 though and but never managed to beat it as sonic thanks to that stupid barrel part, ugh really I remember wasting countless nights trying to get past it before I had to return the game back to Blockbuster. Damn you Sega for that.
3-D wise only played bits of the Adventure games wasn't really all that bad though nothing special. I loathed those hide and seek stages with Knuckles and Rouge though, that constant beeping from the indicator got real annoying real quick.
Heroes was actually pretty good. Closest to the the original series as it could get. Guess the only reason it hated because of the abundance of characters and that voice acting (Seriously they practically babyfied Tails and I won't even get into Team Rose)
Shadow the Hedgehog?….HAHAHAHAHAHAHAHAHA! Oh good joke Sega.
Sonic Riders was a huge letdown cause the premise had promise. But the speed just wasn't there and that air meter was the linchpin that ultimately broke the game down.
And lastly Sonic Next Gen, played a demo of it. Beautiful to look at but that pretty much seems to be what Sega focused on. Controls were too damn sensitive, at least in Adventure Sonic started off slow and picked up speed. Here Sonic practically shoots off once you tilt the stick. Attacking was no better and you think after four 3-D games Sega would take the hint about fixing the camera already. XP
Despite all the faults am still holding out hope SOMEONE at Sega will make a competent 3-D game for Sonic.