I like Gamebox Asia, but the tiles are a little small. They're better on my X50v than my X3i or X5, but still are small. Aside from that, it's a typically beautiful PDAMill game.
I never tried Emperor's Mahjong.
How about Shangai Pocket Essentials by Landware. (
http://www.landware.com/shanghai/ppc/index.html) That looks like a nice version with bigger tiles.