Personally I wouldn't touch anything that wasn't 1st party. For the Xbox you should try out the "S" Controller from Japan... Very sweet ^_^
Pop online mate as they will always have cheaper prices for pads. Pads are universal as well so there isn't a problem about voltages. www.tronixweb.com have the S pads for about $38 USD (£24) which isn't too shabby since the 3rd party pads would be around £20.
Got my Official S Controller from gameplay.co.uk for £22.99. Very nice controller, but I think I'll stick with the original and use this one for my "small handed" friends.
if your games nights are anything like mine with my mates we look for any excuse at all to gain advantage so you will be better off buying all the same official pads mate.besides that when your moment of glory arrives do you really want them saying yeah but you had the best pad etc lmao that what happened at ares.an wouldnt you rmates chip in for the other controllers that way it keep syour costs down an if they arent there you anint gonna be using all four are you lol.
Hmm.. My reply was lost/deleted... Probably because I included a lil joke that I said to my mate offline ^_^ No matter though. Just keep on looking around on the net and Silverback has some good advice. I got my mates to chip in for some extra SNES and N64 pads before.
The S controllers can be got from Amazon for £21.99. If I get 2 then no delivery costs as its over £39! I suppose for the sake of about a tenner I may as well get those.