I have a trainer which I use once or twice a week. What I use 2 or 3
times a week is a Concept 2 rower. I find that a lot more enjoyable to use indoors
that the trainer.

I have some weights, kettlebells and elastic bands I use at home; and I have been meaning to
join a gym.

If I do that it will be twice on the rower, once on the bike or spinning class and twice in the gym.
It's not as bad as it sounds, I deliberately progress very slowly in the gym, and I do intense once
a week and only 3 times a month and I haven't even started getting intense yet except when I shovel snow.

The best exercise is the one you will actually do.

If you like swimming, swim. If you like powerlifting, grunt.

If you get a rower, get a used Concept 2. It's the only brand to get,
and most used rowers have had a very easy life.

Try a spinning class, the pedals are double sided, SPD and Look usually.