Do you want one for a leisurely weekend ride around the burbs or do you want it for transport or will you be cycling on the road?

For a general out and about, short trips, sturdy bike, you might want to consider a mountain bike or hybrid. They are heavier and therefore slower than a road bike but feel more sturdy.

If you are planning long distances regularly I'd probably go a road bike as they are lighter and more efficient.

Don't know anything about belt drives sorry.
Hopefully Audax will pop in. She's an avid cyclist