I absolutely love Vocaloid! My favourites are Rin Kagamine (I like Len too, but he gets too high pitched and sometimes squeaky even if he is a guy who is going through puberty xD lol!) and Luka Mergurine. Some other Vocaloids that aren't really popular I like are Kiyoteru, Chie, Ooka, ISeeU (originally Korean), and IA. I don't care much for Cul or other Vocaloids with really deep sounding or high pitched voices..

---------- Post added 05-07-2014 at 09:28 PM ----------

I have around 900 different songs all together and over 500 of those songs are by Vocaloid alone.. The ones on my favourites list are...

Sakura Song- Chie ft. Ooka Miko
Flowers Bloom in the Night Sky Please Summer!- Len, Gakupo, Kaito, and Kiyoteru
Again- Ib (If you don't know the game you won't understand the reference to any of the songs from Ib)
Memory(Ib)- Rin Kagamine
Puppet(Ib)- Mary
What? Ah, Yes.- Ib
Bringing the Rain- Len Kagamine
Butterfly on Your Right Shoulder- both Rin and Len Kagamine versions
Cinderella Syndrome- Rin Kagamine
Electric Angel- Rin and Len Kagamine
Envy Catwalk- RIB
Shake it!- Miku Hatsune, Rin Kagamine, and Len Kagamine
Hot Cocoa- Len Kagamine
Invisible- Rin Kagamine and Gumi Megapoid
Pinko Stick Luv- Rin Kagamine (not what it seems... <-<)
Kokoro- Rin Kagamine
No Thank You- Miku Hatsune
Remote Control- Rin and Len Kagamine
Sigh- Rin Kagamine
Skeleton Life- Rin and Len Kagamine
Tell Your World- Miku Hatsune
Love is War- Miku Hatsune
Interviewer- Luka
Just Be Friends- Luka
Answer (A continuation of Just Be Friends)- Luka
Music Box of Time- Luka
The Girl Who Doesn't Know How to Love- Luka
Tori no Uta/ Song of the Bird (originally by Lia and opening for the anime Air)- Luka
Witch/ With Hunter- Vocaloid (there are so many of them that sing this song it would be like nails on a chalk board trying to figure them all out, but here are the obvious ones if you wish to know... Rin, Len, Miku, Luka, Gakupo, maybe Kaito?, and maybe some more? Idk if I covered all of them or if there is one extra.. oh well..)