Imogen is one of my favorites. To me, personally the popularity of any name isn't a issue and I only judge it on the people I know or have met. Really how many Imogens' are you going to meet in your life? You meet way less than 100,000 people in your lifetime and there is seven billion people on this earth most with different names so that means that there must be around about three to four billion names maybe more. So really you will only meet around three maybe four Imogens' in your whole life, probably less. I honestly think that too many people make the popularity think a huge issue but it's not. All that should matter is that you and your partner like the name, that's all!
I agree that it doesn't really matter in the grand scheme of things, I just can't help but be put off by it. In an ideal world, my little one would be the only [insert name here] in their school at the very least.
I really like the suggestions of
Georgiana (though I'm not sure how to pronounce it? I assumed jor-jee-ah-na, but I've heard jor-jay-na...)
Adeline (though my sister may have claimed this one)
Beatrice (but I know it's approaching the top 100)
Ivy (as with Beatrice)
Going to take some time to go over everyone's suggestions later, thank you :)