i cant lump it and commend for the brands u mentioned above.... because they are not the same....
azimuth - for copying big pilot?
the design of big pilot doesnt belongs to IWC. B urh is an official design for german wwii pilot.... wempe, iwc, lange, stowa & laco all been awarded contract to make these watches, some with own movement some with swiss movement, the design and specification is from military dept. all 55mm, design to wear outside flying jacket, big crown for easy adjustment. so no 1 owns it now. no issue of who is copying who.beside iwc, there are plenty of german brands making similar design watches, price from hundred to thousand to ten over thousand...
beside wempe, laco, stowa still producing.... surf around, u will find archimede, steinhart, aristo, epos......
some modernize, some evolving, some try to follow original 100%, some big, some small....
parnis, invicta - for copying u boat?
u boat design also not really patented, the canteen crown is also a military design for better water resistant... u can find US army is using this.... but it built smaller! russian diver also same.... but with super huge case....
parnis is obviously copying the u boat bulat bulat....fitted with cheap china movement.... selling cheap cheap!
invicta doesnt copy bulat bulat here but fitted with cheap swiss movement selling to mainly US market....