sliding with big slick

[chipmonk]

Early in a 10 table tourn., I held AKo, with modest stack ($900). Blinds 15-30. After utg called, I raised to $100 in 3rd position, and after 2 callers behind, BB (villain), the chip leader with about $2000, raised to $500. pot=875. After the blinds and utg folded, I called and ended heads-up against BB. pot=1275. stacks: mine $400, his $1500
flop: 864 rainbow.
Then I check-folded after he went all-in. Though I didn't know my opponent that well, I guessed a lower pair (QQ-88) was more likely than AA or KK, and that he might even hold something like AQ, KQs, or AJs. Given these assumptions, which decision was worse, the preflop call or the check-fold on the flop?