What are some good yoyos with a width under 43.5mm and with over at least a 54mm diameter?
Yoyojam Vexed. It feels like a bimetal, heavy but fast, if you’re into that sort of thing. I got mine 2 days ago and was pleasantly surprised that a five year old plastic can do horizontal and even fingergrind. Your specs are pretty specific🙂 do you want a metal?
I have gone through roughly 80 yoyos in the last year. The ones that I have found that actually last and stay in the collection are those yoyos with at least a 54mm diameter (some much larger) and about a 44mm and lower width. Might as well go with what I actually seem to enjoy 
Metal all the way preferably mono metal.
OD code1 is 42mm width I think and it’s one of my favorites to throw
3YO3 Bassline 2. You absolutely will not regret it.
SPYY TYY-01
YYR Laser
YYR Attune
YYR TRIPLET
I 2nd the YYR Attune if you can find one. The laser was nice too but it was kind of bland to me.
For me, the Laser is an excellent yoyo, I use it more often than Draupnir, of course is thought for 3A
Ops… and YYR Clash, and Sleipnir/Gleipnir/Draupnir/Sigtyr/Haeven Seven, ecc.