Hangers and open tanks help a bit with avoiding scratches as an alternative to tray processing. However, for films like Kodak and Ilford, scratching hasn't been a problem for me in trays.
I like using hangers, and they are my preferred method for 4x5. Once I get some bigger tanks I'll be using hangers for 5x7 too. I have a Jobo, but I don't have it set up all the time, so hangers or trays are easier for me than dragging out the Jobo and setting it up.
Stainless doesn't break like plastic could, however plastic doesn't bend like stainless can. In other words, they each have their +'s and -'s, but either work fine.
I have a small stainless tank that holds about 4 4x5 hangers, but I use rectangular plastic kitchen canisters for the stop and fix.
Some people like the "slosher trays" which hold 4 sheets of 4x5 and fit in an 8x10 or larger print tray, I think Bostick and Sullivan sell them. Since the film sheets are separated and don't get handled during processing there is less chance of scratching with these.