I have a QT80 and used to have a QT60. I prefer the QT80. The user interface is more intuitive to me, perhaps because it reminds me of most 2m/440 radios I've had, works very similarly. The QT60 has an interface that reminds me of my old Ranger 2950 and a busy display similar to a Stryker. Not a bad thing, just less intuitive for me anyway.
I wouldn't have known which I preferred until I tried them both. It's a very personal and subjective choice, although you can carefully compare the specs and features online and see if any differences sway you one way or the other (power, size, menu structure, etc.). Both are great radios with impressively high build quality and performance. We are living in the golden era of 10/11m export radios!
P.S. I also have a QT40 which is super fun and nostalgic AND performs great.