renewing F-1 visa is similar to applying for a new one, it just takes less documents. depending on how busy the embassy is, it'll take 2-4 weeks from the day you pay the fees and get an interview date. as long as you have been doing what you were supposed to do as an F-1 student, there should be no problem getting (re-newing) the visa.

about canada- one of my Indian colleagues (she was on her OPT) went to Canada and came back with a renewed F-1 visa after about 2 weeks. So, it seems like Canada might be a faster option, and cheaper too. But it worked for her doesn't mean it'll work for you.