I have little experience in other CAD collaboration software, but my team started to use GrabCAD this year and it's great. In the past we've used Dropbox, but we didn't like it. Dropbox is useful for sharing final files for viewing, but using it on a work in progress is annoying. In comparison, GrabCAD:
- has unlimited space while being completely free
- has a Solidworks plug-in that allows you to update files that are already opened in Solidworks. That doesn't solve conflicting versions, but it does allow someone with the assembly to update the individual parts without closing and re-opening it.
- Within the online 3D viewer, GrabCAD also lets you measure distances and compare different versions overlaid on top of each other.
- lets you create a "partner folder" to create a public link to one of your projects, allowing you to share your CAD files online. It's similar to Google Drive, but it's better because the receiver would be able to view the CAD online before deciding whether to download it to view in greater detail.
I don't know about other CAD collaboration software, but GrabCAD is great and our team will continue to use GrabCAD for collaboration.