Need advice (or opinions) on Buying a Scamp

Both are comparable as far as build quality goes, so what it comes down to is personal preference in the styling, and options.
'72 is a flat nose with the smaller bumpers, '74 is a "beaker" with the larger "impact" style bumpers.
'72 will most likely have small bolt pattern 9" drum brakes all around (if stock), possibly optioned to 10" rear drums and KH front discs. Some service parts are becoming difficult to source for the KHs.
'74 will most likely be big bolt pattern, possibly single-piston front disc brakes- much easier to find parts for. Plus the large bolt pattern will give you more options if you decide to change out to aftermarket wheels in the future.
'74 has the dreaded seatbelt interlock system; if it has not already been bypassed, you will want to address that after purchase.
Is one or both a bench seat car, or buckets? Does one have a preferred color for you? Closely check frame conditions, and simple things like exhaust and tire condition. Has one or the other had too many "hands" on it over the years? Fewer "previous owner" fixes/modifications, the better.
Assuming similar body/interior/drivetrain condition, it's just going to be a preference call on your part.
'72 will currently have a better resale value, if that concerns you. Who knows what the future will hold.