Interesting, at first glance I thought it was [name_f]Sienna[/name_f]. I’d say it see-ahhh-na, might also be tempted to say shah-na because of the similarity to [name_f]Sian[/name_f] (I’m [name_f]English[/name_f] if that helps).
[name_f][/name_f]They’re both very pretty, I think I prefer [name_f]Alessa[/name_f] because it’s more straightforward to say and spell [name_f][/name_f]- I also like [name_f]Alyssa[/name_f] and [name_f]Alessia[/name_f].