Partner Machinery: Same Stats or Different?

I know that PM are different than Mags. However, I'm curious what benefits they provide when you bring them into battle, and also how they act when they get there -- and based on these things, I wanted to know if I should try to go for a PM with the same overall stats as my char, or a different but complimentary one.

So, for example, if I'm intending to be mostly a Hunter, would I want to make a Ranger or Force PM to support me from afar? Or is it best to make another Hunter PM? Or is it really a wash in the end and reliant simply on my personal choice?

I'm personally torn between making a complementary one (AKA Resta) for my hunter or one that will be good at synthesizing the equipment I will use the most.