If you are a custom automated machine builder that has a baseline system that gets engineered to order, I don't know of any software better at that besides IronCAD. But, to get it to work well, you have to be very proficient at IronCAD and set up your models correctly for reuse. Literally, if setup right, any customization to your product designs itself, and that includes all conveyors for plant layouts. It's amazing.
If you deal with a lot of imported geometry, Solid Edge's Synchronous technology is #1 if you have to modify that geometry. Inventor's Any-CAD is #1 if you want to use "native" geometry within your Inventor assembly but don't have to modify it.
Solidworks is an recognized industry standard and "everyone" uses it. It makes working with suppliers and customers a little easier, if data is something that is a deliverable.
There is nothing that prevents any of the software programs from completing any design that one of the other software packages can do. They are all quite capable. It just comes down to what you do most often, pick the package that excels at that, and accept the fact that you won't be as productive in other areas that the competing software is better at.
