I've been planning a solar system for months. The BMS part is one part of the equation that gets complex fast. From what I have gathered, even having a CAN port or an RS485 port does not mean it will communicate with any other device having the same port. It may even be that the cable wiring sequence (pinout) varies from one brand/model to another. For this reason, it is important to know which model of inverter/charge controller/battery/etc. that you need to link up. It is likely that consultation with a good user manual for that device will be helpful in knowing how it communicates--and this, in turn, will guide you to a BMS that will cooperate. In many, perhaps most, cases, the device will only connect using one protocol/method; i.e. if using the CAN port, the RS485 will be disabled or vice versa.
I'm with you on the wish to have a chart comparing all the options in a side-by-side format so that the differences can easily be seen. I have yet to find such a comparison. My humble suggestion, being a novice myself, would be to choose one brand that you have seen favorable reports for, and just focus on seeing if you can make it work with what you have. If you discover while researching that one brand that it has some shortcoming, then switch to another and try again. The existence of various BMSes does seem based partly on having a variety of features that meet a variety of needs, so understanding what you need is the first step in the process.