You also have to decide what you want to carry and where you want to carry it to.

Most of my bike trailer uses are for carrying groceries, plants from friends who don't need them, stuff for camping with kids and the occasional bike. I find that the Nomad – with a few minor modifications – is a good compromise between weight and capacity. My worst loads have been moving earth, sand or salt.
The few times I have more to carry, I either go by car or, more often, get a delivery.

A trailer like the Bike at Work one would suit a few more loads, but most of the time it would be too much of a load to carry around.