SM-57 into a 1073 is my choice for guitar amps, probly 99% of the time!
If it ain't broke, etc. I do want to try out a ribbon mic one of these days though.[/QUOTE]
-good choice...I'd concur alot of the time with this also.....BUT
What I think you need to do to improve your E-GTR sounds, if they need improving is to learn to improve the source. If your working with a good guitarist on a good song in a good room...etc. then a 57 into a good pre, properly placed, really will do the job 80% of the time. The other 20%, going to differrnt mic's, pre's & placements so that you can have separation amonst your overdubs.
I also believe that the majority of people asking these questions are not having the luxury of being able to work on big budget, or with the highest caliber of studio gtr'ists, artist's, etc.
This is where it pays to be able to teach yourself the skills of fixing the source. Crank those knobs and throw those switches on the GTR and AMP. Move the cabinet aroun the room. Experiment with chains of stomp boxes and pedals. In short really get the true sound coming out of the instrument,that you need , relative to it's place in that particular song/arrangement/mix...and this may mean comprimise. there is no one way that anything hast to or should sound. If you can only get so much distortion find another way to get it, maybe re-amp the alrealdy tracked gtr back through the amp for another layer of distortion. My point, in a nutshell, is to think outside the envelope. Mic's and pre's are designed,on average, to reproduce what they get...so by definition the sound you give them is fundamentally whatyuo'll be getting. That said learn those skills I've mentioned. Borrow some gear if you don't have it and learn to do this, so that on your next session with some gtr'st with a crappy sound (who has an inverse proportionally sensitive ego), you can go out and get the sound you need in a very few minutes. You have to be able to do this quick, and improve it to the point that is obvoiuys to all in the room. Once you do you'll get the freedom to work on all the instruments this way. Then you can slide your cans on and quickly move your mic(s) around for that sweetspot(capturing the correct frequency and Direct-to-Ambient relationship for that sound, in context to what has already, and will possibly be, recorded with).
This can be extrapolated to all instruments. If for instance, a drummer comes in with horrible sounding kit with lots resonances, old heads, pedal squeeks, etc...don't get mic's any closer than you have to. Distance will impart room and will blend the kit into a whole...keeping the microscope of close micing from magifiing the aforementioned flaws. It will also be fast. And speed can be a VERY goo thing. Great sounds fast gets confidence from the client. If it takes too long to get sounds, they might start to think you don't know where your going amnd then they'll start to second guess your choices. Conversely once you prove yourself you also get the reverse...,more time...which, because your already fast, means more because you do more with it. They'll be playing sooner and you can get them in the comfort zone that will get the best possible performance from them.
So a good performance, out of parts/sounds that are tweaked at the source...will in most situations positively affect the sonic outcome significantly more than which choice between any two $2k pre's,mic's, etc. Give me a '57 into a Mackie and I'll get a better sound than some one who doesn't know this using any othe mic into a 1073....
...my $1 of opinion
