Which name and why?
[name_f]Gemma[/name_f] 
It’s a cute, similar, less popular name to [name_f]Emma[/name_f], and the nickname [name_f]Gem[/name_f] is just gorgeous! She could go by [name_f]Emma[/name_f], if she wanted.
I don’t even know how to pronounce [name_f]Aria[/name_f]. ARE-ee-a? A-[name_f]REE[/name_f]-a? A-[name_m]RYE[/name_m]-a? It’s less cute, and too frilly in my opinion.
[name_f]Gemma[/name_f] is perfect <3
I’ve seen/heard a lot more [name_f]Aria[/name_f]'s and versions of [name_f]Aria[/name_f] then I have [name_f]Gemma[/name_f]. So [name_f]Gemma[/name_f] has my vote. [name_f]Gemma[/name_f] has the lovely but popular [name_f]Emma[/name_f], but with a twist that makes it different enough that it’s not just anther [name_f]Emma[/name_f]. And it has the pet name [name_f]Gem[/name_f] which is super cute too.
I prefer [name_f]Aria[/name_f]. I like the musical connection, and I think it has a nicer sound. Despite being more popular (although I know 1 [name_f]Gemma[/name_f] and 0 Arias), I think it’s almost more whimsical and interesting than [name_f]Gemma[/name_f]. But I am a bit concerned about the combined popularity with [name_u]Arya[/name_u].
I like [name_f]Aria[/name_f] because of the music connection. I know it is a name that is rapidly rising on the charts and has that character on Pretty [name_m]Little[/name_m] Liars, but I have personally never met one.
[name_f]Gemma[/name_f] is nice, but not really my style. I knew a [name_f]Gemma[/name_f], she was the twin sister of an aquantance of mine named [name_f]Lilian[/name_f].
I like both!
I like [name_f]Gemma[/name_f] because it is unique, cute yet still bold.
I like [name_f]Aria[/name_f] because it is beautiful & feminine.
If I have to pick one I think I might have to go with [name_f]Gemma[/name_f]. You really can’t go wrong with either.
[name_f]Gemma[/name_f] for sure.
Wouldn’t go near [name_f]Aria[/name_f] / [name_u]Arya[/name_u] with a ten-foot pole in the next few years. Game of Thrones, Pretty [name_m]Little[/name_m] Liars… It’s the name I hear most these days, even more than [name_f]Sophie[/name_f], [name_f]Olivia[/name_f], [name_u]Avery[/name_u], [name_f]Ella[/name_f], [name_f]Emma[/name_f] (top names in my area)
I like [name_f]Gemma[/name_f]. It’s a classic name, very pretty.
[name_f]Susan[/name_f]
I prefer [name_f]Gemma[/name_f].
I like both! But [name_f]Aria[/name_f]'s popularity says it’s a lot safer To go with [name_f]Gemma[/name_f]. I do prefer [name_f]Aria[/name_f] musical sound (and the Game of Thrones connection, as I am a nerd), but [name_f]Gemma[/name_f] is nice as well.
I really like [name_f]Gemma[/name_f] - so cute but still sophisticated. [name_f]Aria[/name_f] isn’t bad but I always want to pronounce it Area.
[name_m]Both[/name_m] are very pretty. As an [name_f]Emma[/name_f] lover, I slightly prefer [name_f]Gemma[/name_f].
[name_f]Gemma[/name_f] is a beautiful name
I definitely prefer [name_f]Gemma[/name_f]. [name_f]Aria[/name_f] is too frilly in my opinion, and there are too many variations and too many opportunities for mispronunciation.
I know someone with a pit bull named Gemma, which somewhat ruins the name for me. But, I do love the idea of the nickname [name_f]Gem[/name_f], or even [name_f]Emma[/name_f]. It’s growing on me… 
I’ve loved the name Aria every since I saw the show Pretty [name_m]Little[/name_m] Liars, but I’ve never met one in real life. Beautiful name and one of my favorites!
I like both. Not sure if this is a theoretical question or not, but my preference for one over the other would depend a lot on the surname, as [name_f]Gemma[/name_f] and [name_f]Aria[/name_f] have different numbers of syllables and for the most part different sounds. If the surname was, for example, [name_u]Parker[/name_u], I’d pick [name_f]Gemma[/name_f] so as not to repeat the “ar” sounds in [name_f]Aria[/name_f] [name_u]Parker[/name_u]; if it was Mumford, I’d go with [name_f]Aria[/name_f] so as not to have too many "m"s close together.
[name_f]Aria[/name_f] is my all time favourite! [name_u]Love[/name_u] it so much
[name_f]Aria[/name_f]/[name_u]Arya[/name_u] is a name I fell in love with years ago when I first read A Song of Ice and [name_m]Fire[/name_m]. It was on my girl name list for years. But since Game of Thrones came out I am not sure I would actually use it. It’s a little to pop-culture for me now. It’s still lovely though.
[name_f]Gemma[/name_f] is really sweet. I really like it. Fits in nicely with popular names without actually being overly popular.
I like both names. I like [name_f]Aria[/name_f] because it is so feminine. [name_f]Gemma[/name_f] is adorable. I would probably consider your surname to make the decision. Is your last name very common? If it is difficult to pronounce, I would use [name_f]Gemma[/name_f] as some may not know the proper pronunciation of [name_f]Aria[/name_f]. You can’t lose, both are great.
I like [name_f]Aria[/name_f] more than [name_f]Gemma[/name_f], but they’re both nice.