Love Sandpiper. It is the most convenient to most things in Galveston, but they have now priced me out at nearly 80 bucks a night on weekends in peak season.
Dellenara is a good choice right on the beach on the west terminus of the seawall.
Bayou Shores is decent and convenient, but expect your camp neighbor to be about 10' feet away from you.
Galveston Island SP is OK and about 6 miles out of town.
Never stayed at Jamaica Beach but hear it's pretty decent. About 6 - 7 miles out also.