Last time I used a Flomasta 22199SX which is cheap and did do the job, but found the programming needed the book each time. The old Hortsmann DT2 it replaced was only 4 not 6 programs but far easier to use. With mother I tried a Horstmann HRFS-1 the spec was A1 and wireless, however it kept loosing the RF link and no fail safe, this house used a Nest Gen 3, again faults, in it does not connect with TRV heads, but must admit easy to use, turn outer dial up or down and large display.
So back to basics, the TRV is king with gas modulating boilers, you can get cheap programmable heads, pre brexit the eQ-3 non bluetooth was around £10 and with bluetooth £15, the Terrier i30 was also cheap, since brexit the prices have risen, but the problem with non linked TRV heads is they do not turn the boiler off, so it sits there cycling on/off unless there is a wall thermostat.
So again keeping it basic you want a wall thermostat set so when we have good weather it turns off boiler, so in the hall TRV set to 17°C and wall thermostat set to 19°C and since mounted higher than TRV if weather improves it switches off.
Next stage is programmable TRV and programmable wall thermostat with same schedule so can switch down when not required.
And next stage is linked. Again keeping cost down, only needs one or two TRV's linked to the wall thermostat, likely cheapest option is Hive. Hive has demand for heat system so the TRV can keep boiler running when required.
The Drayton Wiser and Honeywell EvoHome do a fully integrated system including if single channel Opentherm where the thermostat turns boiler up/down rather than on/off. With multi-channel the EPH thermostat can work as master/slave with OpenTherm, but does not connect to TRV heads.
I tried geofencing, and this relies on the TRV as with my TRV head the anti hysteresis software was too good, so took too long to reheat, the Drayton Wiser claims to work out when it needs to close the TRV so is faster at reheating rooms when required.
But this house not heating times, but cooling times which cause the problem, the hall cools too slow, so living room cold before wall thermostat in hall turns boiler back on, unless I wedge open door between living room and hall.
Hind sight, and hind sight is easy, Hive would have been better than Nest Gen 3 which I fitted. But a gnome against the living room door to hold it open works fine.