20 and 29 tend to have more access issues, lots of private land
there are elk but it can be tough to get at them; also more hikers

18,28 have fewer access issues and fewer hikers, but you wouldn't be able to hunt out of the house in Lyons

I'd call it based upon whether you want to camp or not, and whether someone will be along who knows one of these areas well- there is a lot of country in each of those units, and the elk can be in many different places in each... it helps to check a lot of different spots