Each of the main softwares focus on different aspects.
As a result of this each software is best suited for different use cases.
Catia - Product design (if you have dedicated designers and shared components)
NX - Mechanical design such as tooling, fixturing, also can work well for product if you aren't using common components (file linking does not exist in NX and makes this impractical with out a PLM with PDM such as Teamcenter)
NX does beat Catia in fastener implementation and that is the main driver for saying this is better for tooling. In catia you need a lot of set up to get your fastener library set up properly and then you have to place each individual fastener, bolt, and washer.
Creo - Design engineers who just want to make a concept sketch that needs to be redone in catia or nx before production. it's implementation of the neat tools make it so that I am yet to see some one make a clean model out of creo. every creo model that has come to me looking like it was done by some one who had no ide about actual parts and just needed a model that looked right in a cooperate meeting.
I know this is probably going to get me some hate, but there is a reason Catia cost far more than the rest and is still going strong... the models are better quality and there is nothing you can't do if you can do the setup that's required. NX is really only viable because it acquired IDEAS from Ford and bastardized its surface capabilities into their UG software that was failing (I cried when i heard this was their plan, Ideas needed work on their surface generating algorithm but other than that was the best software I have ever used). UG had no surface capabilities to speak of be for that. And Creo (I forget what it's name was before they rebranded) has always been off to the side while others fought for top spot. never great, never any better than good enough. they can be thought of like the generic brand of high end cad. they implament bits and pieces of what works on other systems in a fashion that is just good enough. and good for them! that business model works for them.