Final Fantasy GBA or PSP?

Which is the harder version? I want a little game to carry around while i'm workin w/ my grandpa in construction. The psp looks flashy and a hassle to carry around and i grew up with the GBA, but i like the idea of a new dungeon called the labyrinth of time. I like the old boss themes better, but the music and graphics quality for the psp beats the GBA. Help..?