This is partly an aesthetic choice.
I am a big fan of the room mic sound, because it conveys an impression of physicality to the music that I haven't been able to hear from a fake reverb. For me, I prefer a room-mic approach even in a not-great sounding room. I think you can also get pretty great results recording a band live in a room with a well-placed room mic. Here's a quick example of a live recording I did a while ago where the band wanted a somewhat ambient room approach -
Refund. (Vox were overdubbed)
A few things I've learned: Start by walking around the room where you'll be recording with the sound you'll be recording in the place where it makes noise. In other words, figure out where in the room your guitar amp (i.e.) sounds best while you are (or someone else is) playing it. Once you've got a spot where things sound pretty good, consider any treatment. This needn't be fancy - it could be as little as seeing the impact of moving a rug around on a hardwood floor, or putting some less reflective materials up on the wall/ceiling.
Then try different mics. And don't just think about the sound of the mic, but also consider stereo pickup pattern. Looks like most of the mics you've got handy are cardioids, so this would limit your immediate choices to x/y, NOS, ORTF, or similar off-axis spaced pair approaches. If, however, you can get another omni mic, that'll give you the ability to do spaced omnis. Bi-directional mics would let you do mid-side (1 bi-directional) or Blumlein pair (2 bi-directional mics, and my preference for the room I'm in). The differences available using different stereo approaches can be pretty dramatic - I find the comparison between the approaches an enjoyable exercise. Maybe I'm just weird.
Finally, play around with the height of the mics. There's good reasons documented on the old forum to consider putting a pair of mics taped on the floor, but I'll confess that after lots of different auditioning, my favorite sound in the room that I'm in is about 4 feet off the floor. This is a great time to use the power of many, many tracks on your DAW - record the mic in one spot, then (for example) 2 feet higher, then 2 feet higher, etc. And then compare them against each other. I wrote up an experiment I did using our drum machine a while back with a sound clip showing off the different height results.
Ambient Mic Height Experiment
Of course, if you can get a Josephson C700S placed in the sweet spot in Studio B in Abbey Road, this will all sound gorgeous. But even in less-ideal circumstances, experimenting with room mics can reveal the difference between "gosh, this sounds like an awful version of the close-miked instrument, no thanks" and "this adds great sonic texture to the music".
= Justin