Proviron is closer to a pure androgen rather than being anabolic. It's not really an AI. However, being more androgenic in nature, it can easily overcome some of the estrogen effects and doesn't get aromatized into estrogen it's self.
I personally like it. Many swear by it for preventing gyno...for me it was perfect for libido support...or at least sexual function support. Having elevated libido and not being able to do anything about it really sucks bad.
Currently, i'm on bromo and a-dex because they are what have been prescribed for me by my physician. I prefer caber to bromo for prolactin control but bromo is a few hundred dollars a month cheaper. Adex is working well for me to prevent gyno.
I wouldn't actually trust proviron as a stand alone to prevent gyno if you are prone to it. But you may be one of the guys who just doesn't need anything. I didn't for years, then got it from a prescribed 200mg/week TRT dose of cyp.
Run your proviron with every cycle if you want for libido, sexual function, etc... but have some nolva, adex, letro, ... whatever on hand at all times ... just in case.