I’ve never actually ridden with any of these stables, I lived in Canada for university and rode out east but these are from my very accomplished GTA riding friends. If you wanted to go Palgrave area maybe for less frequent lessons and do more self-training or sub in another trainer, I could help you a lot more with personal experience.
(I tried to stay under an hour using Google Maps, I don’t actually know the Milton area very well! Also, you’ll have to contact a few re. price - they are probably out of your budget)
I’ll second Justin Pope
Stonewood - with Di Langmuir, one of the best you can get in the area, very show centred, a bit far in Pickering depending on where you live and traffic, definitely have experience with trailer ins/meet you at shows (disclaimer asst. trainer Shane is a good friend of mine so this one is the best!)
Wingberry - Yann Candele’s barn, Jill is amazing, very tailored to the individual, a bit jumperish but very successful in the hunters as well, show everywhere in Ontario/Quebec at WEF and the north east US, excellent facilities, great if you are very serious about showing and winning as it’s relatively expensive and you won’t get much out of their training otherwise
Greenhaven - the McKays are wonderful, trailer ins are welcome, smaller stable, lots of show success
Skyland - big show barn but friendly, hunter focused, full year of showing if desired within Canada, trailer friendly
G&G - small show barn focusing more on training horses but I’ve heard good things about their riding program, very individual focused, show As in the summer and WEF/HITS Ocala in the winter if you want that
Parklane - nice and close, fairly quiet but big into shows, do have a required training program for showers, trailer ins welcome
Stoney Fields - high quality, very successful program, big show program, trailer ins welcome, do Canadian summer season and WEF/HITS in the winter, comes very highly recommended, Peter and Lois are fantastic hunter coaches
Quaker Valley - with Erin Howard, very well regarded, big show stable, exclusive, not sure about trailer ins
Northridge - The Hayes will sometimes do private lessons or workshops with high class riders if you’re in that group, Ainsley’s fantastic