Hi there, first time poster.
I own and operate a quad bike business in Australia and am after some advice on what the best handheld UHF would be for me.
I understand this is a broad question but wanted to see what else was out there.
We have hilly terrain but nothing mountainous.
At the moment we operate 5W Uniden but it is staticky in a few places.
Our furtherest location is around 2kms.
Is it unrealistic for me to think I can find something that will be clear all the way around our property?
Any helpful advice on what I can use would be greatly appreciated 
Being honest, it’s not radio make and model - that just impacts on features, reliability, spares etc, it’s topography. You need a repeater. Even a portable one will make big improvements. A 6m guyed sectional pole and some guy ropes will fill in many of the black spots, especially if you can locate in on the higher ground. You could build one into a flight case with a leisure battery and have it run all day. Downside is cost and convenience, but if your area is simply too difficult, it’s the only proper solution. There is no magic “buy this radio” solution.
Is vhf frequency not better than UHF as VHF usually has better range in open terrain.?
In practice, there’s so little in it - VHF helical are less efficient than a 1/4wave UHF, but UHF does generally get spoken about as if somehow inferior? The Police in the UK used UHF for years and it was pretty good working to portables. Cars with decent length antennas? Then VHF has advantages. you pays your money and …