my answer

Do u have h1b visa on ur passport, if yes, even it's expired, u can use ur valid i-94 to come back if ur trip to canada is within 30days.

However if u don't have H1b visa but probably only ur original F1, even u have valid H1b I-94, u have to apply for US visa application in Canada. This should be favored over applying for AP, coz the latter often times let CIS assume u abandon ur h1b status, thus it's risky if 485 does not get approved.