Synology seem to be some of the better ones.
There are other brands that are alright too, and I'm one of a few people around here who built their own. But to paraphrase what they used to say about IBM, nobody ever got fired for buying Synology.
Look at the specs before you buy - if you can get one with ECC RAM, an Intel CPU (not ARM) or both, you'll probably be happier in the long run. (Those are higher end features.)