Maybe something like Miku Dark would work if you want a less squeaky voice, but then again it kinda falls in the husky area both Luka and Gumi occupy. Nowhere near as much, of course, as it's still Miku.
What I really like about Miku's appends is that they genuinely sound different from the base voice, especially Miku Dark (probably her only voicebank I can appreciate), which is something that got lost in other Vocaloids (cough, Luka.) because people complained the appends were too different :/
Yeah, I could literally barely tell the difference and only used Luka's "Straight" for the song I did. I guess I can understand if people want to be able to transition between the different types in a song without it being too jarring, but it's still pointless if it doesn't change at all.
I think if Miku's pronunciation has just gotten better, I'd be open to giving her a shot. "Sharing The World" is just painful to listen to, because it's not even a decent approximation of what the word "sharing" is supposed to sound like.