Yeah, Alan's magic based, and likely it would be a draw.
Without significant prep, Strange would have a hard time mustering up enough raw force to just overpower a GL, and most GL's are versatile enough to negate and/or lessen the effects of most of Strange's tricks.
Still, Strange is more versatile in the long run, and stuff that he does regularly (dimension-hopping, time travel, kncoking out Abstract-level beings, etc.) are things GL's only do on their absolute best days. The GL could win, but he'd have to make it a short fight.
Draw 5/10. Strange wins 3/10. Alan/Hal wins 2/10.