In message .uk, Ed
Sirett writes

Worcester-Bosch & Vaillant have good reputations for reasonably-priced
kit

Gloworm & Ideal may also be OK

Potterton/Baxi have ground to make up on their reputation from past
products (and the way they've handled problems with them) so, other
things being equal, I'd avoid them.

For general criteria see Ed's boiler choice FAQ

I note that Baxi who swallowed MAIN some while ago are now badging the
boiler as MAIN. The product is identical (AFAICT) to a Potterton model.
I guess they may eventually run out of reputable names.

The British Leyland syndrome ...

--
geoff