The Tacx Vortex Smart provides progressive resistance without being plugged into electrical power — something few lightweight and portable smart trainers do. However, it requires power to provide controllable resistance and power data. It doesn't win any awards for power accuracy or road feel, but it is a reliable training tool that is somewhat more versatile when used as a warmup tool compared to other trainers we tested.
On this end of the price spectrum, the Vortex's most obvious competition is the Kinetic Road Machine Smart, which costs less, more stable, and finished higher in overall performance. The Kinetic is unable to communicate via ANT+, though, limiting its connectivity compared to the Vortex.