SF4 feels fine with a pad because they intended it to be played (okay) that way. Older arcade games, like MvC2? Even HD Remix? It feels harder to do some stuff with a pad, IMO.
Yeah SF4, because of the shortcuts and leniency on input, is much more pad-friendly. I did alright with my 360 pad but I was unable to use Ultras on command because of the macro buttons spitting out EXes when I want an Ultra and vice versa. On top of that, FADCs are nigh-impossible on the 360 controller.
I tried a Fight Pad, got the Chun-Li one, and it broke within two days, so I took it back and pre-purchased Super with the refund. I liked the pad quite a bit, but the fact that it's lighter than its own cord and MadCatz-durability are a huge turn-off to me.
The stick ended up being the only option, and I don't regret my purchase. Can't wait to get it on with Super and MvC3.