I went for a Lacie 2big one this time. It seems very well built. Had a couple of QNAPs (209 Pro and a 219 I think) but they both died on me after a couple of years (one taking both disks with it.)
I like the Lacie as it doesn’t try and do too much. I really only use it as a TimeMachine backup, though it can serve media. I have a Mac mini that’s always on that I use for any services.
I use to run loads of stuff on the NAS but they tend to be quite low power, not much memory, and generally seem to run a lot better if you just use them for storage and not as a mini server.