As good as a ready-to-buy arcade controller can get, I really recommend you making your own arcade controller
http://arcadecontrols.com/arcade.htm
I was around 13~14 years old when I made it, and it's still functional today
it was based off a regular usb controller, I just made the case and soldered the buttons to the contacts on the controller. (basically, you just move where the short happens, where the button really connects both contacts on the original controller). I had no previous soldering skills, and for that age, you know it shouldnt be hard to anyone
It was a great thing for me to look into electronics (and most certainly, one of the reasons I ended up studying electric engineering later on
)
the looks isnt that great, but believe me, they play real great!
design is really important, so really take your time to think what's the best for you. Even after looking at all those controller designs, I really knew I wanted 4 straight buttons for neogeo gaming, but I wanted them in-line. with 8 buttons, I have 4 in line for neogeo and 3+3 for games like marvel vs capcom. I choose then in-line because I think some designs that try to make up to your fingers length end up weird and not that comfortable. Also, I chose two separate players because it's not always that you want to play standing, sometimes you just want to put them in your own lap and play
anyway, get inspired by others design, and make your own. either if it's for the pandora or a regular computer/laptop in mind, you can be sure you will have lots of fun and lots of nice things to get learned by making it. needless to say it's a pleasure to have your own work done