From what I've understood lately 6100 would be the one replacing 2530 as it does not have dynamic segmentation support or any advanced features like EVPN/VXLAN. Wonder if it will have stacking though? Probably not that either if it's replacing 2530...
6200 does not have EVPN, but static VXLAN support. So it's quite similar to 2930. It has dynamic segmentation.
6300 then has EVPN/VXLAN and dynamic segmentation and you can do a mixed stack of F and M series.
I believe otherwise the exact details are mostly irrelevant for most users so it's about how much you need those UBT/VNBT (dynamic segmentation, EVPN/VXLAN) features or mixed stacking of switches with dual PSUs. (Only point I see with 6300M is dual PSU. And .. well that's one expensive second power unit I have to say :) ). Last time I asked, 6200F was a lot more expensive than 2930F, and no one could really say any good reasons why to go with 6200F. Wouldn't like to go with AOS-S as it's clearly being phased out so hopefully next year we can get better quotes :)