I recently bought a 2023 GTS SuperTech coming from a 2021 Genuine Buddy 170. Here are my unsolicited, biased thoughts:
Some background:
I've been riding 2-wheeled things since 2010 in L.A., Portland, and San Francisco.
GTS:
The engine is so much smoother and quieter
The acceleration is more linear and controlled
Seat is roomier and ample room on the floorboards
Way better suspension
Those LED lights are nice and bright
Buddy:
Lighter and easier to muscle around
Non-covered shelf on foot shield is an advantage
Switches (turn signals, start button, horn, etc.) are higher quality and have better actuation
Bigger and cooler underseat storage
I loved my Buddy and there are definitely things I will miss, but the smooth power and upper end capability of the Vespa easily wins in the long run.