My pad journey:
Corel Draw '93 pad. I think it was like 6x8". 0.5 inch thick. Hilarious. I still have it.
2010 - steelseries SX: (10x12") great aluminum pad, nice low friction. After about 3000 hours (a little bit over one year), it started wearing down. It was a very loud and scratchy pad, but very slippery. It also ate mouse feet like no tomorrow. I switched it out because it was actually too small.
2011 - Steelseries QCK+: (15x17"). So i was out of town for a while, and i wanted to game so i needed a pad, so i grabbed the biggest cheapest thing i could get, and it was this. Lovely pad. Tracking was not as good as the SX, and it had higher friction, but holy crap it is quiet. Nice for travel, but i'm super lazy so I don't like it for extended use. It also gets gunk stuck in it.
2012 (present) - C4 ngen 04: (16x16"): Lower friction than sx, lower noise level than sx (still makes corduroy vwoop vwoop sound), better tracking than sx and less mouse feet wear than the sx. This is my favorite surface. Like any "hard" pad, it does get dirty, but you can wash this in your tap. Works best on hard glass or plastic surfaces, where you can wet wipe them clean and quickly apply the pad. I have a dinged up wood ikea desk that swells when it gets wet, so its tough to get this thing PERFECTLY flat because of the wood bubbles, but other than that it is amazing. I love this thing. You have the hugeness of a soft pad, with the low friction and sweet tracking of a hard pad.
HOWEVER, it likes big thick mouse feet like on the logitech g9x or corsair m60. Thin mouse feet like on the steelseries kana seem not to agree with it. If you consider one of these, do yourself a favor and buy the c4 mouse feet with it, you will not regret it at all.