question

It doesn't really matter, both as functional and reliable.

With multiple devices, it is easier, possibly cheaper to wire a chain of CAN devices, rather than individually linking devices back to the GX via VE.direct.

The choice is yours. I doubt you'd see any performance differences.

VE.Direct is a point-to-point unbalanced serial connection where as VE.Can (aka CANbus) is a balanced (RS-485) multi-drop connection. I think VE.Direct came first in the Victron world.

VE-Direct requires a connection on Cerbo, etc. for every device and at most there are 3 ports. You can extend this by using a VE.Direct to USB adapter cable.

VE.Can is physically different from CANbus. VE.Can uses ethernet cabling, looping through each device. CANbus uses a unique connector with "taps" to go to each device. You can interconnect VE.Can to CANbus with the appropriate adapter. The entire network is terminated at both ends with a 120 ohm resistor. VE.Can/CANbus is limited to about 100 devices. VE.Can/CANbus operates at one of several baud rates and in the Victron world, this rate must be the same for all devices on the same port. Additional VE.Can ports can be added to Cerbo via a USB to CANbus adapter.

VE.Can is used, if you have the MPPTs with the VE.Can option, which allow you to balance certain settings across the MPPTs, like the Voltage settings and maximum charging current.

For this setup you do not even need a GX device because it works entirely Stand-Alone!

I have now a SmartSolar MPPT 150/70-Tr VE.Can together with my two new SmartSolar MPPT 250/100-Tr VE.CAN. No Color Control GX or Cerbo GX needed.

You will not see any difference in performance (speed wise), but VE.Can is somewhat more resistant to electronic interference (inherent feature of CAN, as is of RS485).

Because CAN has a daisy-chain-like bus topology, it's really well suited for larger installations where you would have to use way too many VE.direct ports (remember: OctoGX is not around anymore). Also it allows for somewhat longer connections/distances.

Last but not least it allows you to snoop on the bus. ;-)

In the picture above you are (ab)using VE.Can for a P2P/direct communication which, given the fact that the Cerbo has 3 native VE.direct connections, is misplaced love - sort of.