I made a simple plugin that allows you to search for models that look roughly the same.
Let’s say you had something like this:
and you wanted to select all the trees. This would be difficult to do manually since these models haven’t been properly named.
Introducing Select Search By Sizes!
A revolutionary new way of selecting models! 
You simply select what you want to search through, then (while holding CTRL) select what you want to search for.
With a click of a button, Select Search By Sizes Plugin selects the models that looks similar to the chosen model.
How does it work?
It gives each model a unique ID based on the sizes of all the parts inside said model. Then it compares these IDs with other objects to tell if they’re roughly the same.
It also rounds these sizes to whatever you have snap to grid set as.
If you’ve made small modifications to some models, but still want to select them, simply increase the size of your Snap to Grid Move Studs.