I really like
Arielle. I'm not a fan of
Ruth or the repeated r of
Arielle Ruth, however, many people like that sort of thing so it all depends on the individual.
Other fn suggestions with three syllables:
AbigailAdaraAtarahAvivaBethanyDamarisDelilahDrusillaHadassahJemimaJoannaKeturahMiriamPenninah
PriscillaShoshannah /
SusannaTabithaTalitha
Hope this helps.