[name_f]Adelaide[/name_f] is my favourite name from your list. However, I’m not sure it goes with [name_m]Ian[/name_m], though you may not mind that. I think [name_f]Evie[/name_f] sounds lovely with [name_m]Ian[/name_m].
I adore [name_f]Adelaide[/name_f] and think it fits with [name_m]Ian[/name_m] better than your others which are more modern.
[name_f]May[/name_f] I also suggest [name_u]Evelyn[/name_u], which you could shorten to [name_f]Evie[/name_f] as a nickname? Or [name_f]Genevieve[/name_f] (which can also be shortened to [name_f]Evie[/name_f])
[name_f]Evie[/name_f] works well!!
I’d also suggest
[name_f]Gemma[/name_f], [name_f]Adeline[/name_f], [name_f]Nora[/name_f], [name_u]Hadley[/name_u] and [name_u]Piper[/name_u] came to mind
[name_m]Ian[/name_m] & [name_f]Adelaide[/name_f] sound adorable together. [name_u]Henley[/name_u] is too trendy for the classic [name_m]Ian[/name_m]. [name_f]Evie[/name_f] is pretty, but more suitable as a nickname for [name_u]Evelyn[/name_u] or [name_f]Eva[/name_f].
[name_f]Adelaide[/name_f], 100%. Also really like the suggestions of [name_u]Evelyn[/name_u] or [name_f]Genevieve[/name_f] to get [name_f]Evie[/name_f].
[name_f]Evie[/name_f] is adorable and goes really well with [name_m]Ian[/name_m]! Another name I thought of was [name_f]Abigail[/name_f] “[name_u]Abby[/name_u]” or [name_f]Ebba[/name_f] (even though I know that name isn’t everyone’s style).
[name_f]Adelaide[/name_f]-This is lovely. Feminine, yet not overly frilly. It’s not terribly popular on its own, but if you add up all of the ‘[name_f]Addie[/name_f]’ names, you’re likely to run into a bunch of Adelyns, Addisons and Adelines.
[name_u]Henley[/name_u]-As in [name_m]Don[/name_m] [name_u]Henley[/name_u]? I don’t care for this. It just seems like a random trendy ‘lee’ ending name. And also not very feminine. Not to mention, [name_m]Henry[/name_m] is so popular for boys that this is bound to be mistaken for that a lot.
[name_f]Evie[/name_f]-I love Ee-vee, but not Eh-vee as much. I think that people will mostly say ‘Ee-vee’ when reading this. I’d do it as a nn for [name_u]Evelyn[/name_u], and then it makes a little more sense.
I like [name_f]Evie[/name_f] best, but agree with pp that you will get “Ee-vee” a LOT. I’ve know two “Eh-vees” - one spelled it [name_f]Evvie[/name_f] and one was an [name_f]Evy[/name_f]. I’d spell it [name_f]Evvie[/name_f] or [name_f]Evvy[/name_f] to get the pronunciation you want. [name_f]Etta[/name_f] is similar and also quite sweet.
I think [name_f]Evie[/name_f] and [name_f]Adelaide[/name_f] go better with [name_m]Ian[/name_m] than [name_u]Henley[/name_u]. What about [name_f]Hattie[/name_f] or [name_u]Halle[/name_u]?
Based on your contenders I also would suggest: [name_f]Eliza[/name_f], [name_f]Audrey[/name_f], [name_f]Cora[/name_f], [name_f]Briar[/name_f], or [name_f]Maisie[/name_f].