I'm super biased because Hephaestus is one of my favourite of the Greek gods (I have a few but it's hard to like a lot of them) but I do really like this name. It's not the hardest Greek name to say (that's not saying much but it's pretty easy) and the classic form (Hephaistos) is also very nice, just more uncommon. It can be (and usually is when Greek myth nerds are talking) shorted to Heph which I like. Heph was probably one of the nicest and calmest gods (it is hard to find that combo in myth, but Hades and Hestia were kinda okay) so that is a plus. Good namesake, good pronunciation, good meaning, good overall sound.