In general, is PLA or ABS better for functional prototyping?

I recall that I printed a rectangular box of about 1 cm thick and about 10 cm long using both ABS and PLA. The one made of PLA using Makerbot 2 bent easily but the one made of ABS using Up Plus 2 did not bend that much and seemed to return to the original shape when I did not try to bend it. However, after applying some more force, it broke.