I am on my third one in about 10 years and my recommendation is to get the most expensive one you can find. My first one was a small convenient one that could not adequately suck all the air out and it would just run and run until I manually stopped it. The second, more expensive one did the same. The last good bigger one has been working quite well.
I use the more expensive bags for long-term food storage and non-food related items. The items I use short-term I use the cheap-knockoff thinner bags.
If you plan on re-sealing something again and again, make the bags bigger because when you open them and re-seal them, you lose about an inch or two. I have learned not to make the bags too small since it makes it hard to seal when you don't have enough room to lock the bag.
I only re-use them if there is no raw meat or ingredients in there. Salmonella is not fun.
"If it is going to happen, it's going to happen out there." Cap'n Ron.