I've got a Trafalgar Paddock Cleaner. The red plastic bin one!
It is very easy to use and picks up anything and everything. It has no problems in wet grass and I find it great for the scattered bits of poo in a field, as it doesn't leave a single piece behind.
The plastic container can be washed out and obviously doesn't rust. The poo doesn't go through a fan, so it doesn't get blocked.
I have a tow bar on mine (although I tend to move it round the field by hand) and then tow it to the muck heap.
I'm going to sell mine and hopefully upgrade to the one that is self propelled.
I've got a predator, you tow it behind a tractor/atv/landy and its fantastic. We have noticed how much you don't pick up or miss when you hand pick. It apparently can even suck water but haven't tried it.
Does take a bit of effort though, the easy tip ones might be better if you are working on your own and if there is 2 of us (1 on tractor & 1 on sucker) then it does sometimes cause arguments!! lol! We never agree when to move on in time with each other!