Both have pros and cons.
Dual boot -
pro: More accessible to hardware and you can utilize the 100% of your hardware resources.
cons: Not very easy to set-up for beginners and may crash your original/main OS if you can't properly set-up.
pro: Easy to set-up and do not effect your main OS.
cons: In maximum, you can utilize the hardware for 50% like cpu. Can not access the hardware directly form Virtual Machine.