Well, I think Water is as well, only because it's very versatile, doesn't have a crapload of weaknesses, and has several dozen Pokemon of its element, so you really have options as to which Water Pokemon you would like on your team. I'm not saying it's the strongest, but I am pointing out this strength that makes the game more fun. Lapras? Gyarados? Blastoise? Starmie? Use whichever one you want, they're all overall decent (although Starmie and Lapras trump out of that group). You can have Water/Grass, Water/Ice, Water/Flying, Water/Ground (ouch)...
And guys, before one of the mods takes a stroke, try to put a little explanation behind your results rather than one-liners.