WhateverMadov. He and Dubois are both much alerger men with much larger frames than Sirenko and Gorman. Sirenko is in some areas the most skilled of the three, and in other areas I think one of the other three is. The problem for Sirenko and Gorman is I don't think they have the size, strength, athleticism, height/reach, or power to be anything close to a threat to a top 20 fighter. In the modern age of SHW's, you need to have good head/upperbody movement and the speed, athleticism, IQ, and footwork to get out of danger and into your range. I don't think either of them have anything close to enough of any one of those things to be able to have continued success at the highest levels at HW. And I certainly don't think they have the power to catch the attention of any of the top SHW, much less deter them, nor do I think they are comprehensively skilled enough in a diverse amount of ways to do anything but faceplant on some people's expectations of their prospects. I don't think either of the other two are anything special either, but they both have MAD LEGIT punching power, repertoire, decent at setting up their shots and knowing when and where to throw what shot/s, and the size, strength, and certain skills to make themselves relevant, and I suspect whateverMadov has a cast iron chin and excellent overall durability and also think Dubois will prove to have a great chin and durability too. It's totally conceivable to me that both could stick around and be contenders or at least top 20 relevant for the foreseeable future at HW.
Makmuhdov has waited too long to turn pro in my view. By the time he gains enough fights under his belt to be challenging for a world title he will be around 33 and thats already post prime. Dubois has more of chance than Gorman, he has serious power and a killer instinct which you need to be able to get into the top 5 and stay there. I think Gorman plateau's out at around top 20 in the world. I have only seen bits of Sirenko and he is a nasty vicious man, which is always a plus but its too early to tell based on the level of opposition whether he is capable of being a future world champion.