I did a lot of research into this a while back and soon learned there are two main types of small manure spreaders. One is like a long trailer with a conveyor belt and rotating paddles at the back and the other type is like a big mesh drum driven by direct contact with the wheels with a gravity actuated beater.
A quick trial of both and it was a no-brainer for us. The conveyor belt one threw the manure out everywhere, including over the operator

, without breaking it up at all - might just as well have driven around in the truck and shoved it off the back.
The rotating drum OTOH, only lets stuff out that is smaller than the holes in the mesh, which means nothing is left in the paddock that won't break down relatively quickly. The beater did break up the manure effectively and the machine gave a nice, fine even spread.
Sorry, I don't have time ATM to add links, but a search will quickly show the conveyor belt/paddle type and the drum type can be found without too much difficulty, though they did seem less common when I last looked.
BTW, try comparing expected maintenance/repair liabilities for both machines.......
And both could be towed OK with our 18 HP ride-on mower, though a bit more power would've been useful.