Well, I had to vote all four because what I like about Nacchi is the whole package. There may be others who are better singers etc., but only Nacchi has it all and more to me~
I didn't actually instantly fall for her. It was only after I learned more about her ridiculously cute personality and also saw her appear serious in Pinch Runner that I had to kick Yuko out from #1 spot and take Nacchi instead. (Yuko was probably my favourite only for the first few weeks of my fandom or something? But I was learning fast!) And ever since her personality has really drawn me to her. Her sense of humour is just so silly and goofy and her reactions to things are hilarious. Yet at the same time I can tell she's also ambitious, a hard worker, and a warm person in general. She has this lovely, light spirited aura around her that makes me happy when I see her.
But yeah, personality isn't the only reason I like her
I also find her mad attractive. Whatever she wore and whatever she did, I'd be attracted to her. It's crazy - I just badly feel like I need to touch her (not necessarily in a pervy way guys, even just something like hugging or holding her hand or brushing her cheek). She's incredibly beautiful, cute and sexy, yeah... I absolutely love her face. And that smile, oh dear lord x_x She doesn't have a "traditionally hot body" like Rika (with a slim waist etc.)... But Nacchi is just perfect for me. Perfect weight, height. Soft and huggable, cute little toes even. So also her looks and body are something that draws my attention to her.
And her voice, I love hearing it around, makes me feel all comfy and at home. Not really the prettiest singing voice out there, I guess, but important to me and she's worked hard to do the best she can with what she's got. Because her vocal capabilities aren't perfect and I acknowledge that, I still sometimes get impressed when she sings something better than I expected or just sounds extremely beautiful. And I actually find that very satisfying and cool. So even vocally she's perfect for my needs as a fan
So yeah. Thanks for giving me another opportunity to praise Nacchi o/