Pro E seems to be quite good, and SolidWorks is ok. I never used Pro E, but I have used Mechanical Desktop, Inventor, SolidWorks, SolidEdge, Alibre, TurboCad, about every version of Autocad, and CoCreates Solid Designer.
The best I think is CoCreate hands down, bar none. I really dont care for the history based programs. I work a lot with existing designs from other engineers or customers. Those history based seem to be a pain to try and run threw the features to find the problem or add new ones in. SolidDesigner is a little hard to figure out, but once mastered it runs circles around the others. Its not history based, and is setup for more of the high end, bigger complicated designs.
I am a subcontracted mechanical desinger/tool designer to HP and other high tech firms. I constantly design, or modify designs of assemblies with over 1000 differnt parts with ease. It runs out to the sixteen decimal place, so accurarcy is not an issue. There are designs and models I have done, or seen I have showed to other users of the mentioned software and they simply state they cant do some of the features.
The down fall is the 2D side is ok, not great, but by good enough to get the job done. The cost is around 7k, and support is still teething. CoCreate used to be an HP product only, they owned it, therefore no one else expect HP had it. CoCreate spun off on its own, orginated in Germany, and now is a private company. So its relatively new, meaning the company is teething on manuals. For solid modelling, speed, complicated designs, and complicated assemblies, it simply outperforms anything else I have yet to run.