Cost must play a part. ETR kit is much cheaper on the used market and 645 is still a noticeable jump in quality over 35mm.

A bit of hunting will find an ETR (or more likely ETRS, if you're lucky ETRSi) with WLF, 75mm lens, 120 back and crank for 150 or so. That gives you a camera which produces negatives twice the size of 35mm but in a relatively compact lightweight package.

Having used a 1930s 6x9 camera a week ago I found it very difficult to use in portrait orientation. Luckily I can just turn the "brilliant finder" sideways and shoot it landscape instead, which would be very tricky with a WLF.