First, make sure you get an N router (A,B,G should already be supported) as you will get the most out of your iPad even if your internet is not as fast as that (and it probably isnt with the avg being between 10-20 mb)
Second, and this is a personal one, Linksys is the brand I have used for more than 12 years now, and they have just worked. I have upgraded them to new models basically when the bandwidth of the wifi has increased.
So long as you don't go out and get the "well, this supports N and it is $15" version of a router, you should be ok.
Just remember, at least get a router that supports N. It will make streaming (if you do that) much better.