Just about every stream, I get asked about my cycling setup.
I use Zwift, which is the game I play to ride in. It has workouts, training plans, races, group rides, or just low-stress free rides. I was an early adopter and was in their Beta back when they started. Warning: it can change your life.
For Zwift to be able to do all the things to make you feel like you’re riding in their world, it needs a smart trainer to talk to (which changes the resistance on you, like you’re going up or down hills) and a cadence meter. It can use less smart trainers if you have a power and/or speed meters.
Smart Trainer
I use the Wahoo Kickr first generation smart trainer. I can’t say enough good things about it. I mean it’s just a super-heavy hunk of metal that I never see because it’s my back wheel, but it just works. It’s always worked and it shows no signs of quitting after several years.

Learn about the Kickr here. (affiliate link) They have a number of options for smart trainers ranging in price. I haven’t exactly been researching smart trainers of the years, but from what I hear, they’re still the best of breed even though much competition has arrived.
Cadence

For cadence, I use the Wahoo Cadence sensor (affiliate link), which connects through bluetooth to Zwift (and my cycling computer when I’m outdoors. more on that later.)
Heart rate monitor
So that’s all the bike stuff, but what about your body? You can’t really understand and improve what you can’t measure, and heart rate is how you do that. I’d say heart rate monitoring is crucial to this setup, even though it’s optional.

I use the Wahoo Blue HR heart rate monitor. It’s always worked great for me. They have newer versions now like the Tickr pictured above, which you can check out here (affiliate link).
My Road Bike
My bike is a Parlee Z5. They don’t make it anymore, but here’s my bike on BikeRumors. I built it myself from parts. That was fun and rewarding and because of that and the 12,000 miles I’ve put on it, I have a strong emotional connection to this bike.