Depends.
One speaker may sound different from the other.
Put you ear right up to each speaker with the guitar playing at a safe volume.
Listen for any tonal differrences.
Pick the one with the tone you like better.
One mic is easier to set up, obviouly, but two mics gives you a lot of options ..... both tonally and stereo options .
You must really pay attention to phase issues (i.e. lots of mic placement trial and error) when using two mics.
You could just as easily get the stereo options from recording the single mic twice which I prefer for rythm tracks but some times widening out a lead track from one take with two mics is nice.
I like two throw up 2 or even 3 different mics at first when I know ultimately I will only be using one so that I can get a rough idea of which one is working better within the context of the rest of the mix ....... then tweak.
But I prefer 1 mic on clean tones generally.
If you go for two ..... a SM57 and large diaphram condenser together yeild a huge array of tonal options.
refer to these treads also:
https://homerecording.com/bbs/showthread.php?s=&threadid=33141
http://www.recordingproject.com/articles/article.php?article=25
-mike