Hmm, that's a tough one. What I do have to say, is that I did Not like his singing voice in LBT 11 very much
It's really a toss-up, as the others were all reasonably good. This is in my biased opinion, as I have always preferred Littlefoot's voice from LBT 2 - 4. I must also say that I liked his singing voice in this range of films (Kids Like Us, anyone? B) )
His voice in Always There is very nice, and suits the song beautifully. His voice also worked for Lone Dinosaur, though I have to wonder if Littlefoot's voice from LBT 2 - 4 would have done a better job of Lone Dinosaur, as he had a stronger voice, generally. The softer songs, including When You're On Your Own were done quite well by Littlefoot's singer in LBT 6. For the most part, he is very good as well.
Littlefoot's singing in LBT 9 and 10 was also very well-done
Adventuring was done very effectively, and No One Wants To Be Alone was very sentimental and flowing. I loved Littlefoot's LBT 9 voice for this song.
Overall, I don't really have a strong preference for the singing aspect, though for actual character voices, I miss both Littlefoot's and Cera's voices from LBT 2 - 4. They were still my favorites when it comes to voice acting.