I have and adore both! Diana actually kept saying the exact same dialogue except about Marshal xD I'm a little more biased to Diana because she's been in my town longer but I wouldn't give up either of them.... 3 normals is a lot though. I have 2 normals and I don't know if I can deal with another one (normals have the best design though in my opinion- I wish some were other personalities like Skye, Marina, Merengue, etc so I can have all of them in my town). xD It's ultimately up to you though.
I think Diana looks stunning, so I'd probably keep her.
On a completely different note, as I was reading your post I thought "Hey, I recognize that Totoro shirt.." and realised that's what Flurry is wearing, since you let her move into my town a few days ago. Thanks again for that! She's a cutie, I really adore her.
Diana is my second favorite deer after Beau. She's one of the nicer snooties imo and i love having her in my second town, Palette. I was tempted to move her over into my main town but i decided against it. Fauna is nice looking but there are more normals that i like a bit more than her.
Snooties talk about the other villagers. It just happens. Ankha talks about Muffy all the time, but they never fight. Or really see each other since they're on two different sides of town. Any snooty you get will do this. I've had Fauna in a cycle town and she was really sweet. Ultimately get who you want. Diana is one of my dreamies for my second town, so I like either really. I guess I'd go with Diana since you have 3 normals, but I have 4 peppies in my main town right now, so....
If Diana's snooty remarks upset you, don't keep her in your town. She will not change and she will not stop saying those things. Keep villagers in your town that make you happy. It's okay to have lots of one personality type in your town if you like them all!
But don't make a snap decision. I am someone who is very sensitive and easily upset, so I find that it is best to give a conflicting situation some time and thought before I decide what to do. If you are not a cycler/time traveller, I would wait until one of them asks to move out and then evaluate how you feel. You might have made up with Diana by then, or you might not like Fauna as much anymore.
edit: lol I should really start checking the dates on things >.<
I love both of them. ;3;
If I had to choose I'd pick Diana since you have a ton of normals. What she said about Flora is just a generic thing snooties say, my Whitney always says that about Mira. -w-