It all depends on what you will be using the ipad for. I bought the 3G iPad and was the biggest mistake I ever made. Wasted 130 bucks when I only used the 3G once. I bought it originally thinking i'd go on and off with 3G whenever I needed it, and that never happened. When I did take the ipad out, it was normally somewhere that had a wi-fi connection.
So this time around, i'll be sure just to get a wi-fi only ipad.
Also with the wifi hotspot that should be coming soon for at&t, I'll just share my iphone's internet connection with the ipad. So there would be no point in me getting a 3G iPad anymore.
Everybody is different though with their uses, so it's all up to you.