Just for reference for future visitors of this thread. There's also pretty complex Assembly 3
, which is in development, but the Octover's release was a giant leap forward in terms of stability. There should be also a new release by the end of this month (November 2018).
Some bugs are present, but it is fairly feasible Assembly tool, once you get to use it. The most troubling is solver behaviour, he often needs to change parts position in order to solve the constraints.
Also there's currently no other way to put assembly (3) into drawing but through part WB -> Crate Copy -> Create a simple copy command. This means every time you change something, you have to crate a new copy of the object and replace the linked object in the drawing view(s).
It has to be said, though, that Realthunder's Assembly 3 is not only a workbench, it's a fork of FreeCAD highly modified, with amended infrastructure, such as Link concept. This means, that models created in standard FC and this fork are not directly compatible. Assembly 3 can modify FC models to it's standards, but there's currently no way (I know of) to convert them back.
A2 is pretty simple, but strait-forward and good work bench, however I had a lot of troubles with more complicated models. In such extent, that it rendered to be unfeasible (for large assemblies). It doesn't complain as the A3 solver, but it the A2 assembly simply "explodes" at some stage and I couldn't find way around it...
I didn't have chance to test A2plus yet.