Because there are so many great fighting games to play on the PC, you really need to check out the fightsticks that are compatible with it.
Order your Kombox Impact preassembled with Sanwa buttons or in DIY format, and there is a joystick edition too.
The Atachon BEATdown is an all-key controller that looks like a cassette tape, and it has extra keys for the left pinky & right thumb.
The Haute42 M16 can also be a WASD controller. As for the M13 edition, it has three less buttons than the M16.
Choose one of more than a dozen all-button layouts when ordering the slim and mini SL-X controller from BattleMonkey.
The Punk Workshop Leverless U provides a plethora of features, such as slimness, many layouts, different colors, and custom art.
The nanoGRAM is the size of a card, making it one of the smallest Smash controllers (if not the smallest).
The GRAM PRI$M allows you to play Smash and other titles ergonomically with a variety of possible layouts.
The SGF Faust is a mini stickless controller with LED plus a TRS jack for external input sources like foot pedals.