design best practice says, try to have less number of virtual switches, preferably one.
but then requirements coming from customer would definitely be ultimate goal.
scenario 1: create 1vds switch with 4 port groups (all uplinks go to 1VDS)
I would go with this and do Virtual Switch Tagging (VST)
scenario 2: create 4 vds switches and each port group under them. ( different uplinks go to different vds)
if there's a specific need to achieve complete physical separation, and I am not allowed to do VST, then I will go with this scenario, here I still have leverage to do External Switch Tagging (EST).
Narendra Padmani
VCIX6-DCV | VCIX7-CMA | VCI | TOGAF 9 Certified