Here's my opinion, although I note I haven't formally reviewed any of the pubs.
The Queens Head is a good shout - it had a refurb about a year ago - and you also have the Three Tuns and the Metropolitan within a couple of minutes walk. Some of those do a CAMRA discount I think and sell decent ales. I'd forget the Fig Tree (which is an old police station from which the Metropolitan opposite got its name)
I wouldn't bother with the JDW, it's quite depressing. As is the Irish bar a few doors away.
The General Eliott is OK and, although both are a bit 'tired', you have the Dolphin and the Pipemakers Arms within walking distance. Be prepared for the latter to be closed though, their opening hours can be sketchy.
The pubs in Denham Village are also a good shout, and all close together so you can get a cab and walk between them.
I'd also endorse the Hop & Vine in Ruislip if you are stopping off there. For some reason PuG does not show walking route from Ruislip tube (Piccadilly Line) but it's a fairly straight route and only a 10-15 minute walk.
Enjoy the day.