It depends what sound you want. If you want that âaudience taperâ sound, then omnis, but unless youâre experienced, itâs hard not to get too much atmosphere, and not enough main instruments. I certainly couldnât when I recorded myself that way. Ask Dan for advice if this is the direction you choose.
I would place SM57s on the amps, myself. I wouldnât worry too much about bleed, youâre going to mix it all together in the end.
That said, âbothâ is the choice of professionals. They like to mix some ambience with the close-microphone recordings for âthat live soundâ. And you certainly have enough microphones to pull it off.