Depends, whatever you like with other games will work just fine in Marvel2. Being comfortable is key. People do swear by their MAS sticks, but I noticed Sanford is playing on a TE stick these days. It really comes down to what you like.
Basic pros/cons of the common sticks when playing this game…
**Happ/Wico Perfect 360: **
Super smooth. Ton of travel/throw so good for people who put their arm into it. Though the engage is actually pretty small, so you dont have to ride the gate either. Really good for HGxxTempest and rolling out reflies and spit fly unfly spit and all that good stuff. Durable and dont have micro switches, so you can basically forget about them once installed.
On the negative side, since its a stick with giant throw AND small engage distance, it can be unforgiving if you have sloppy execution. For instance, even great Magnetos throw the odd accidental boomerang when rushing the tri-jump motion. Some P360s have very bad diagonals, usually requiring that you swap in a smaller actuator.
Essentially the same as the P360, but has switches. Not as buttery of a circular feel, but still very smooth. Diagonals are easy to hit and dont vary from stick to stick either.
Assuming the use of a square gate, you will never have trouble finding the diagonals, even under pressure. Easily customizable in terms of gates and springs. Can’t really knock the JLF, it does everything pretty well, basically the Ryu of joysticks. JLF has a really big dead zone, so it is very forgiving in terms of execution.
Sanwa Flash, Toodles Spark, Rollie Flash, ASCII Optical:
Basically the same as the JLF, just less maintenance. The Spark (CE model) stands out in that you can dial in the sensitivity of the optical switches to make it more or less lenient depending on your style.
There are a bunch of Seimitsu options, but generally they have harder springs, shorter throw and faster engage. They are less forgiving than a JLF, due to a smaller dead zone, but are optimized for a lot of quick, small movements (think shmups). More suitable for finesse work than elbow grease.
As far buttons, its almost 100% preference on how they feel. Though technically there is a tier list for buttons when it comes to mashing, simply based on how fast the button switches return after being activated.
Happ > Seimitsu > Sanwa.
Where Happ is better by a bunch, and the other two are neck and neck with Seimitsu a little faster.
That said, the difference is still minuscule and knowing how to mash whatever move is way more important than having a special mashing button. Lolz.