I've been out with Ridelines (only a short course) and Dirtschool a couple of times. They're both excellent, no wrong answer, but I think they have different strenghts.
Andy Weir at Ridelines is a better teacher. He seems to get more out of people and is more encouraging/supportive, and I thought his explanations were clearer. And his class management just seems better. (more on this) Meanwhile Andy Barlow at Dirtschool is probably the better performance coach from what I've seen, I reckon he can lift you higher and faster- but you need to be a bit more motivated and focused. He's brilliant solo or in a small group.
The only criticism I have of Dirtschool is about the class management. In the 6-person class, 1 person was in the wrong class entirely, but instead of addressing that he ended up spending a huge amount of time with them, while others got very little time. That's a tricky situation but I felt like we all subsidised them. And in the end we didn't quite cover the full course as we spent longer on basics. Not ideal.
But, the coaching I did get was excellent, so it was still a good day and worthwhile- it just stopped it being five star. But I think at the end of the day, if you're doing a group course (especially at the lower ends) Ridelines would get my money. For solo coaching or a more advanced course, I'd probably go back to Dirtschool (I did!) But I would happilly give either my money and I can see me going back to either in the not too distant.
Phew! You are spoiled for choice.