Goodness, that's quite a collection!
Phoenix - I do know a boy called this, I was completely shocked when I first heard it! I think it's a bit crazy! but if you like crazy, go for it!
Jules - Nice, but Julian is nicer then you have more options.
Bowie - awful, unless you are super die hard David Bowie fans.
Jett - many dogs are called this, it's as much a dogs name as Spot, Patch, Fudge to me.
Hendrix - there was a character on Neighbours called this, It's ok, but people will probably assume you are massive Jimi Hendrix fans.
Ziggy- as with Bowie.
Asher - alright
Jesse - really like! I don't think it fairs well in Scotland though.
Harley - meh
Ozzy - are you Australian?
Onyx - I have no idea how to say this.
Cosmo - bit bonkers, but i think it's liked on mumsnet.
They're all a bit off the wall, but if that's who you are then why not?! Also if you live in a trendy part of London these names will probably go down well, or another city with a lively music and arts and culture scene, Liverpool?
Good luck!