Both much of a muchness in terms of quotes.
Builder A - Long established (50 plus years) family firm. Have lots of accreditation - federation if master builders etc. Recommended by a friend for whom they did some work recently. The guy who came out was very friendly, professional and gave a very reassuring impression of their service and capabilities to deal with the job efficiently. The quote is reasonably detailed but there are a couple of changes/details to be confirmed e.g. Haven't had a site visit by plumber or electrician to confirm minutiae of exact requirements.
Builder B - one man band type company. Came across as friendly and thorough in his approach. Clearly doesn't have the same history of experience/reputation as the other. However, has been very detailed in his quote e.g. sent plumber, electrician round etc first. I suspect the service will feel much more 'personal'. However, no recommendation from anyone I know.
After A left I felt really confident and impressed. After B left I thought 'let's see what he come back with', but have been impressed with his communication/detail since. Wwyd?