The features of a good commuter pannier are:
Quick-release locking system: not elastic, velcro, non-locking hooks.
Good stiffening on back and base, that is not too heavy.
Heel cutout shape.
At least one pocket.
The toughest material you can afford.

I managed with cheapo flimsy panniers with hook and elastic but my caradice are tougher, stronger, more durable and more convenient to use. If you are going to use a bike as your main transportation, sooner or later to have to bite the bullet and get some good ones, or make them.