Soft coolers don't, as a rule, insulate as well as hard coolers. They also tend to fall apart more quickly. I have a hard Coleman cooler that's older than dirt and still does the job admirably well. I've never had a soft cooler last more than about one season of regular use.

On the other hand it's much easier to carry a soft cooler around for occasional use, and if they're small they're much easier to carry.