It says imgflip pro will let your memes be on top of the approval queue

you mean just for the case of 1) Latest sort, 2) streams set to no auto-approval, 3) moderators doing large batches of approvals just once or twice per day? you may be right for that case.

For auto-approval streams though, images do not go live simply in the order that the moderator or system approved them, they go live in randomized batches, so being approved first simply means a higher chance of going live faster.

This is why when I had pro in October, I approved my images last in streams that already had approvals.