One question I get quite often is the age-old "Which guitarist do you think is the best?". This question can—of course—be approached from many different angles: are they asking about technical proficiency, or perhaps sort of highly subjective "musical" variance here? I always presume they are talking about that magical combination of the two which unfortunately means any answer is more an indication of my prefered blend of these two musical components than any sort of critical analysis of performers.
My favourite trick here is to parry the request by switching to the question of my favourite instrumental albums. This has three main advantages: Firstly, it is much more musically pure. I have always been of the opinion that the chief artistic output of a (non-classical) perfomers is the LP album, in much the same way that a painting is to a painter. (This concept has always been pleasing to me for a variety of reasons too verbose to list here, but it probably stems from the classical concept of the composition)
Secondly, it helps to highlight the factor of time: remember that styles of many artists change dramatically throughout their careers — check out Richie Blackmore, Kevin Moore and Greg Howe for classic examples of this.. Comparing albums allows us to focus on a 'snapshot' that is more easily analysed, especially with regard to its context with other albums.
And lastly, comparing an easily obtainable and well-defined part of an artist's discography ensures there is little or no discrimination against people who haven't heard every rare and/or esoteric B-side or studio out-take. For some reason, I find this is usually a problem with Steve Vai fans..
Of course, restricting my choice to almost purely instrumental performances cuts out some very historically important guitar-heavy albums—I can quickly think of Hendrix's Electric Ladyland, the entire early Deep Purple discography, and (arguably) David Lee Roth's Eat Em' And Smile here. Now, I must agree that although this is a totally valid point, without this restriction the scope of this list would be enormous as well as being rather unfair on early artists who did not start to record albums for many years (for example, B.B. King's first single was released in 1949, but his first album was released in 1960).
So stay tuned, you've got number 5 heading your way tomorrow.