I vote for the second one.
It´s similar to the NI Guitar Rig Control, that I´m used to.
There it´s called "prev" and "next" which makes sense to me coz of the order left and right.
BUT! I can also get used to other orders.
The main thing is to get the looper AND that we don't need to wait another year.;-))
Down Up I II III IIII
1 2 3 4 5 Tap
On the other hand I do also agree to
"Raoul23"
"The down/Up buttons are prefered on the right side because they will not be used as much during a performace as the I to IV buttons would."