Is there anything to choose in reliability of the electronics or
TRV's between various manufacturers?

Electronics are normally reliable. I'd buy a room stat mainly on the basis
of appearance, provided it had the required functionality. Brand in itself
wouldn't matter to me, except in that a good brand is more likely to
physically look better.

TRVs should be from a reputable manufacturer and expect to replace every 7
years or so when they start to get a little slow. Cheap ones may fail in a
couple of years.

Christian.