My opinion may not mean much since I don't post here often, but here's my 2 rings (terrible pun... Lol)
Personally, the 3.0 Sonic is the best yet. Enhanced air mobility, less knock back on stale moves, and kills off N.Air around 90% ~ 110% makes Sonic ALMOST OP, but in a good way.
Combo ability, INCREDIBLE SPEED, mobility, grab range, Sonic has everything he needs to be top tier. Everything, and those who dissagree... Well... You may be playing him wrong.
Of course, with soo many great plus's, he has to have a couple weaknesses. Literally I only see two weak points: Weapon characters, (sword users, space animal technology) and his weight.
But here's the thing. He's got F%£k'in AWESOME MOBILITY! So it doesn't matter how easy to smash he is, if you can't hit him to do damage, you cannot kill him.
I did pretty well at one of the local tourneys here with him, and I'm sure I've got a lot to learn. Thanks Project am team for making my favorite game character sooooo awesome.