Staring down the throat of a hard reset as we speak, i vote for Sprite. I don't know about sunnysoft, but the SPB beta that I am beta testing does not include persistent storage. This is a must for me because, i found out the hard way, that some files want to convert and not simply copy if you don't use a back up program.
I talked to SPB about the persistent storage and they did not see the need to provide it
Activesync is a lot slower for me, so it's Sprite for me.