Thats a tough one and everyone's experience will be different. I was in your shoes years back and opted to buy Maschine MK2 new and it had hardware issues, screen and encoder, out of the box brand new. It took a considerable amount of time before I ever got the MK2 replacement, but what I got was good up until I opted to purchase a brand new MK3, which also had encoder issues out of the box and the replacement I received is again exhibiting the same encoder issue within the same year unfortunately. For me, buying new at least gave me the option of being able to go back to NI and show them the issue and ask for a replacement in good working order. Buying used, you may have to pay for some additional parts/replacement so it may help to keep that in mind when weighing your options.