I love high-intensity classes: spinning, boot camps, the old-school body pump at Gold's Gym. I don't belong to a gym now, but love that so much good content like this is available for free on youtube. I was late to the Peloton obsession, but absolutely love mine.
On the contrary, I hate low-intensity classes like yoga, barre, pilates. I know they're working me out, but they're so slow and boring that my mind wanders and I feel like I'm wasting time. Ditto for classes that have too much down time - either rest periods or huge amounts of time to teach you choreography.
And swimming - so so so so boring. I want to learn to love it, but I can't.