I've an older food saver and a black & decker. I prefer the food saver. Keep the b&d in the rv for use in the summer time. As was said, they get you on the bags. However I cut my bags larger than they need to be and clean and wash them up to be used again several times before tossing them when they get to small.
they will all do the job when it comes to sealing "hard" items. The problem with some of the older or cheaper ones is they don't allow you to stop sucking air out before you squish a "soft" food item. For example, certain types of vegetables like peppers or tomatoes. I happen to have a cheaper one that does not allow for this so the next one will have this feature.
As for the bag or rolls, I like having some of each on hand. I prefer the "simply smart" brand as they are the thickest most heavy duty bags I have seen. I picked up a bunch from fleet farm when they were on sale.