From my experience it's fairly competitive, but it even depends on the year. I was awarded an OGS last year, but this year I was waitlisted. My application only got better for this year, but I was told that the pool of applicants at my school had much higher GPAs this year compared to last (closer to 90s).
I'm waitlisted at Guelph. Basically there's no way to know your ranking unfortunately. Seems some people have luck with their departments or grad offices telling them if they're highly ranked and giving a couple days notice that they'll get an offer, but that's pretty uncommon. Most just have to wait it out it seems.