I suggest you go on reading forums where people talk about this indepth specifically. Visit the forums of the software companies you have mentioned, read the threads there, ask some questions and also ask what people think in regards to competitive software (some forums allow mentioning competition, you need to see how it is on a per forum basis).
Other than that look for forum where people talk about 3d modeling of mechanical parts, read and ask some more, ask people to tell you their experience.
Visit software developer home pages, compare prices and features, check if they have options for a perpetual licence or if they only have options to rent (or both), decide which is better for you by weighing out cons and pros, download trial versions where possible, run the software to get a feel for the interface. Watch tutorials of where people show how they model and use the software (yes for each software you are thinking of choosing).
Take notes and compare overall.
This needs time and commitment if you are to choose what is best for you, and there is no way of winging it.
Pretty much 3D software from the top shelf targeting a specific industry should be similar in capabilities, but I think you should strive for an industry standard, a package which is required by most companies in a specific field, when they recruit.
This is too specialized to ask on an open forum like Fiverr in my opinion, where most posts are about people complaining about not getting gigs and asking for work all over the forums.
However, what I have posted above is how I would go about this matter if I was to pick a 3D software package for myself in any field, if I was to start my 3D training all over again.