It's easy to just flash one, try it for a bit, then flash another and compare them. You could even make a nandroid backup of each one after you get it set up and customized a bit so you can flash back and forth to really get an idea of how they differ.
You also need to consider whether you want to use the old partition layout or the new one, as that will determine to some extent what your options are for ROMs. They're not all available for the new layout just yet.
I'll be doing this exact thing today with SlimKat, MeanBean, Carbon, and a couple of Sense 4.3 ROMs.