I've unlocked the Stealth, Hunter and Terror styles but can't imagine ever using them. Each handicaps you in a different way, so I guess they're mainly for providing alternative challenges, but they definitely don't make the game easier. One of them takes away your sword. How is that helpful? I use my sword ALL THE TIME.
The hunter outfit is the one I've used since I unlocked it. Having two attack items is amazing.
The hunter is probably the best one you can unlock via secondary objectives, but honestly I still prefer the default suit to it. Two attack items is great, but I find the fact that the hunter doesn't restock at checkpoints to be a huge pain in the ass on the later levels that are mobbed with Stalkers and Elite Guards. You can't really kill them silently without items. Not in NG+ anyway.
If I'm going with the default suit I tend to kill Elites by smoke bombing them then running up and stabbing them. And if I have to kill a Stalker when there's nothing in the environment to use I tend to just throw flesh eating insects at them lol.