Ira - it’s Ok in an old man sort of way. It’s probably about to come madly into fashion.
Ivor - as above but a bit less so.
Christopher (not a fan of Chris though) - if you don’t like Chris don’t use it. You could try imposing Kit but it won’t necessarily work. Cassian maybe?
Gabriel - nice enough, overused. Gideon maybe?
Peter - technically due a revival but Pete is awful. Patrick is much nicer IMO and mostly they do get called Patrick (outside of Ireland anyway)
Thomas - nice.
Girls:
Ishbel - love it. So underused
Ivy - nice but overused. Zoe? Ida?
Ava - nice but done to death. Aster, Astra, Elva.. ???
Tamsin - always makes me think of Tampax, and is slightly awkward to say, apart from that very 70s. I think Tamara is better somehow, or Tara, Natasha, Saffron have similar vibes without the suggestion of feminine hygiene products (you know how kids are.)