GamesWorkshop's miniatures vs alternative 3d prints

I am looking to build an army soon (leaning dwarf at the moment but would eventually want to build multiple) and I am trying to decide if I should try and get GW miniatures or use models from an alternative maker (whether that means printing my own or buying them already printed). I was wondering if anyone has both or seen both and how do the GW sculpts and casts stand up to alternatives in terms of detail but also style/theming? I was also wondering if anyone has had success using GW and alternatives in the same army? I ask because I much prefer the original gyrocopters to some of the alternatives so would probably want to get some of those even if I was to get an alternative army. I also don't really care about any potential cost differences at the moment and I assume for the most part 3D printed miniatures would probably be cheaper than GW miniatures.

tldr : Ignoring potential cost differences, how do the GW miniatures stand up to alternatives in terms of quality, style/theming and has anyone found success mixing GW minis with alternatives?