Would you prefer buying a Wi-Fi only device against buying one with cellular connectivity or vice versa?
I think it's better to buy a Wi-Fi only device for the following reasons:
1) if you have Wi-Fi access in your work place or home.
2) if you have a phone that has Wi-Fi hotspot.
3) it's cheaper
4) No need for multiple subscriptions and no need for multiple SIM cards.

And it's not like you'll be on the internet all day long on your tablet, there are other uses for it. That's my opinion, so let me hear yours.