If you must paint it, poplar. It's as much a crime in my mind to paint
maple as to stain cherry...
I built a maple rocking cradle for the 1st grandchild. Tho it will only
be used 6-9 months at a time and infrequently, I'll bet that cradle is
still around and being used 3 or 4 generations down the line.
Are you building a utilitarian desk or an heirloom? Your decision.