Which VM is better at isolating the guest traffic from the host? Windows HyperV or VMWare Workstation Player?
In terms of host/guest isolation, either should theoretically be fine unless there’s some big vuln in VMware in particular, though both ultimately would be using Hyper-V underneath anyway, assuming you have e.g., VBS enabled (which you should) since VMware cannot run the VMs itself fully when VBS or other features requiring Hyper-V are enabled (see here)
If the goal is to isolate network traffic between the two, you run into the problem of isolating east-west traffic within your network (assuming the VM is connected to your router to get internet access), and you would need a complex network setup to properly split the host and guest traffic within your network