My thoughts on these three scooters:
UScooters GT Smart Edition - better ride quality than your Glion; faster; ridiculously durable / good build quality and easy to service if any issue arises. Truly ultra-portable and will fit well with your lifestyle of bringing it everywhere. The GT has the best fit-and-finish of all the the scooters you listed.
Don’t underestimate how getting a little bigger and heavier can make something go from ultra-portable to annoyingly portable.
That said, the City and Mini 4 Pro are going to be better all-around scooters.
Apollo City - definitely a team favorite with slightly larger, air-filled tires and better suspension than the GT. Faster; more comfortable. Company has strong reputation for post-purchase support. Tubed tires may get flats. A really great all-around scooter.
Speedway Mini 4 Pro - we haven’t reviewed this exact version, but the EMOVE Touring is basically the same (and it looks like a lot of retailers have discontinued selling the Mini 4 Pro). Another great, all-around scooter in similar thread to the City. The Touring excels at ride quality; has has a giant deck (increased comfort) though overall dimensions remain fairly compact. Touring also has high ground-clearance which is nice for dropping off curbs. Downsides on this guy are slightly smaller 8-inch tires (vs 8.5-inch on the City). The Touring also compromises by having rear solid tire and front air-filled. Flats are most common on the rear, so this will greatly reduce them, but you still get benefit of front air-filled tire. Overall, another great scooter backed by VORO which also has good reputation for post-purchase support.
I threw these scooters into our comparison chart so you can see how our performance tests compared: