This was something I was back and forth on for a while, initially I was looking at buying a new GTI in July of this year, but I started seeing photos inside-and-out of the mk8 GTI, and didn't like the direction the design overall was taking. I wanted a GTI from the time the mk4s were new, and so I definitely had a certain set of predispositions I favor.
My biggest dislikes on the mk8 were the front end and interior. Having test driven a few mk7s and talking to owners in my local SCCA region, the 7.5 seemed to be the way to go -- so the hunt was on! I wanted the 6MT and plaid seats, so thankfully my desires lined up with the less expensive examples available. BEC/Ed's HID options satisfied my desire for good lighting (the factory reflectors are awful, in my opinion) and so late last year I found a 2019 GTI with a titch over 13k on the clock, falling very nicely into my affordable range. I also didn't like the color options available, Great Falls Green and White Silver were at the top of my list, and so mine being white silver was just icing on the cake.
The digital/touch interior is also a turn-off to me, I like the visceral feedback of buttons and knobs, though the volume/power knob icon rotating with the dial is infuriating but easily resolved with cheap vinyl. I'd like to retrofit the backlit overhead buttons, and I'm still very skeptical about VW/Audi sunroofs, after having issues with my mk4 sunroof and the tales of rattling/problematic mk7 ones I felt the S was the way to go.
A higher pricetag, combined with the oddly-specific desires/featureset I had in mind ultimately pushed me to a mk7.5, and I've got no complaints to date. I don't think the mk8 is a bad car, and I'm sure it will wind up with plenty of VW fans scooping them up for it's advanced features and sharp looks. But I think it's moving in a direction away from what has drawn so many people to the GTI. Even with a little power bump and new tech features, I can't get over the unusual aesthetic of the mk8. But I'm getting long in the tooth, so I may not be in touch with current trends. It definitely seems that the EA888 Gen 3 is a winner though, and the MQB platform seems to be knocking it out of the park for VW.