not having to look up an sp, text/call, make an appointment etc etc
If you go with a big agency it can just be a matter of, "I'm NAME (, ROUGH AGE, MAYBE ETHNICITY). I'm available for a DURATION session between T1 and T2, in PREFERRED AREA. I prefer X, Y, and Z. Is there anyone who is available who you think would be a good match?". You might also want to specify your max price, if an agency has an expensive top tier.
Try that about 10AM, when agencies typically start responding. You'll usually get 1-3 options back pretty fast. Quickly look up their profiles and reviews. Pick who you like, or politely decline, and done.
An agency will always suggest someone, so do some due diligence, but they will usually try to line you up with a good fit. Not quite as easy as just walking into a MP, but you'll probably get better results with only a handful of texts. GTA people are spoiled, despite the price.