Depends on your use and where you will use it ...
Agreed. The 16GB is too small. And a wifi iPad just requires a bit more planning if you are going out-e.g., update your Instapaper articles before you leave the house.
Me personally wifi 32 gig ... More space and no monthly bill .. If I need Internet somewhere I would find a hot spot or use the hotspot from my phone ..
OP - you'll miss the space before you'll mill cellular connectivity... I think it's pretty unanimous... plus you'll save yourself $30/month in data plan fee