The Bluetooth LE stuff is meant to be good but you’ll need a computer with Bluetooth 4.0 or it won’t work (newer Macs are ok, and you can get a dongle for some versions of windows.) If you do get the wahoo ones that do Bluetooth then you can easily run trainerroad on an iOS device too.
If you really want to get into the data then you can export your workout as TCX files from TrainerRoad and load them up into software like TrainingPeaks or golden cheetah and do loads more analysis there.
FWIW I’ve been using the Garmin speed and cadence sensor with a garmin HRM, a garmin ant+ USB stick and TrainerRoad for a few years now. Really good experience (I do have a power meter though.) Everything then goes into TrainingPeaks for analysis.