I don’t know.. That’s too difficult to choose… .

well I love … The Day Aria ,True True Friend, You’ll Find Your Place..
I guess Seasons’ Ending Episodes’ songs are the best.

Personally, My favorite singer is SIA, when I notice they collaborate with MLP, I was so excited. 
As The show’s existing member, I love Ashleigh Ball ‘s voice sooo much.
I think she take 40% on the reason of my OTP(also favorite character too).
I am weak in voices..