WB 42CDi - I like it. Simple to operate (2 knobs for DHW and CH temperatures), fast and quiet. Looks neatly laid inside (I hung around whilst my favourite GasSafe chap installed it).
Good clear installation instructions (I'm not GasSafe and wouldn't touch gas obviously - but I did read first so I had some idea of flue constraints to work out possible installation locations plus requirements for the electrics which I provided). The manual has good clear data too, like maximum system volumes, which we exceeded, so needed to factor in a secondary expansion vessel. WB are also very good on the phone, and are happy to clarify data even to an end user like me.