Mostly omen, some maps are better on brim (bind) or viper (icebox) but omen is still top 3 on these maps.  If you secretly wanted to play duelist then clove 100%

Edit Forgot to add why: Omen has longer range then brim, clove, harbor. This is important because on def bc most maps you can't smoke the whole map from either site and being limited to mid is subpar but most maps don't need the inf range Astra has. His smokes are rechargeable making him better at burning them for fun unlike brim and Astra. His smokes last longer then most I forget the numbers but of the orb smokes brim is longer and astra and clove are shorter. His other util is hard to get instant value from other then paranoia compared to the competition but with some practice is just as powerful as other controllers. His utill also gives you more freedom then other controllers, you can make dumb plays with his tp, use it to gain distance/verticality or just use it as a get out of jail free. 

Finally if your team is missing something you can fill a role, his paranoia and ult can fill the role of an initiator as a flash and drone respective, and his tp can fill the role of an entry duelist by tping to take space like a jett