Advice on What to Buy

I need to know the opinions of you guys which of these two are the better unicycle?

Also can someone tell me the major differences between them I dont see alot tbh.

The biggest difference between those is the crank lenth. The Qu-ax trials has 145s and the hoppley has 127s. This makes the Qu-ax excellent for trials type riding, while the Nimbus is geared more towards street style riding.

The one you want to get depends on what you plan on doing. If you are mainly going to be hopping on everything you see, you probably want the Qu-ax. If you plan on doing a lot of tricks on it instead, get the hoppley.

Could I not just buy spare cranks for if i wanted to do both?

go hoppley

How come?

You could if you really wanted. You can do trials and tricks on both of those unicycles, but generally the longer cranks are better for trials and the short ones are better for everything else.

crank lenght is a matter of opinion
I find long cranks better for everything because you have more control, more torque and i can go just as fast as i can on 127’s