If you want reliability I'd avoid the 2.5" drives in an external enclosure. The 2.5" drives themselves are very rugged and reliable (designed and built to 'mobile' usage specs).
Buy my experience with the USB enclosures for these drives, (have some from three or four different manufacturers), is that the enclosures are the weak link in the setup. Two that I have short out if you press then the wrong way (a regular occurrence if you carry the enclosure in a laptop travel bag). The drive is held inside the enclosure with two micro screws. The circuit board in the enclosure sometimes needs two USB connections to get sufficient power to operate -- you'll usually get a "Y" cable, two USB ends in parallel, and one end that plugs into a connection on the enclosure. So you may end up using two USB ports to power this up.