I prefer glue. With hot fix only the back of the stone gets glued, and sometimes they seperate from the backing. With glue you can catch the side of the stone too
I've done dozens of dresses with hotfix ... handwash them, throw them in skate bags ... a few that are over 8 years old are now being used by our youngest, and never lost a stone. With glue, maybe because I'm uncoordinated, I get frustrated with "glue leak" around the stones, and I'm always terrified about dropping bits of glue on the material, and they sometimes slide from where I put them ... the hotfix ones go down soooo easy, and they hold forever. It could be because I do a two-step process with them: they get hotfixed, them I put a pressing cloth over them and "iron" them to double-set the glue.
Then again, I also like sewing on big rhinestones - that's my favorite way to put them on - done some dresses with 1-inch rivolis on straps that are sewn on ... those things don't move at all
In terms of cost - don't have to buy glue, and because I can do them very quickly (over 250 SS30 in an hour) - it saves me valuable time. Plus, I order in bulk, and the cost difference isn't too much from my supplier ... who is local, so I'm lucky there.