An exterior latex is best for T1-11. There are some good exterior paints out there. I would try Behr or Glidden. Just remember that although you should get several years out of a good paint job it won't last forever.
T1-11 should be coated with latex exterior primer, and then top coated with a name brand exterior finish paint or solid body stain......Hint; tinting the primer to match the finish paint makes the job go easier.
