If you're looking for best bang for buck then that's probably going to be individual programmable TRVs used in conjunction with your existing wireless thermostat.
Beyond that the Conrad system is also good value and adds more features.
Nest looks good but functionally I don't see the benefit over alternatives.
Evohome, while expensive on the face of it, appears to be the most complete and feature-packed system. I've been looking into DIY Z-Wave alternatives and there's not a huge price difference tbh. I'd say its price is reasonable for a premium offering in this niche.
Beyond that the Conrad system is also good value and adds more features.
Nest looks good but functionally I don't see the benefit over alternatives.
Evohome, while expensive on the face of it, appears to be the most complete and feature-packed system. I've been looking into DIY Z-Wave alternatives and there's not a huge price difference tbh. I'd say its price is reasonable for a premium offering in this niche.