Park N Fly has been my go-to parking facility whenever I fly off Pearson. I don't find the Self Park Lot significantly better than the Economy Lot, so for me, it is Economy Lot or airport onsite parking.
The Economy Lot is quite inexpensive for a week of parking if one prints a coupon online beforehand ($52 taxes included). I have waited up to 15 minutes for a shuttle occasionally. The Valet Parking shutter is supposed to be within 8 minutes, but I have never tried.
The coolest thing is the 1 hour grace period. I have had an experience that the 1 week deal ended at 6pm, but we departed the lot at 6:52pm. The machine did not charge us for the extra 52 minutes. In contrast, the grace period at airport parking is 20 minutes only.