As someone who partakes in this I could chime in with some recommendations, this is just a list of SP's I've seen who still post:
Ruby Lust - My first many years ago at her in call. Very sensual and is truly the red milf

Would recommend for anyone whos looking to try it out, or wants to do a switch experience
Mistress Mercy Rage - Had a spicy duo with her an Lana when they came to town this summer. Rates are pretty high but it was an amazing experience and filmed some of it. She seems to be traveling around Canada so not in Ottawa right now. She would be for more experienced subs as it was a hard dom session
Lana Archer - Same as above with Mercy, rates are on the high end but you get a high end experience. Also travels around Canada and I don't believe she's in Ottawa right now.
Skye - Fun experiences with Skye, had an amazing in call location. Only offered dom & a massage. Also I don't think she's in Ottawa right now but she comes back every so often. She also likes to smoke weed and will share
Sadie May - Same as Skye as they both used the same in call. Seems she has moved her in call since I've seen her. Very good experience with Sadie, would recommend for anyone who's looking to try it out
Mistress Jasmine - Had a great experience with her, she turned up the brat to a max but kept it sensual as well. She had really good rates and offered many kinks. Only negative is her in call location wasn't the nicest as it looked like she had just moved in, but she told me she was going to do some upgrades to it.