Is there a difference in the time it takes to aim down sight depending on the different sights? and in general which is preferred.

Yay... a non-complaint thread.

No there isn't a difference in ADS time.

In my opinion a Red Dot sight is needed for the SCAR because of it's muzzle flash obscuring your ironsights, this is made worse if a laser sight is used. (However get 100 kills with Laser Sight and Assault Scope for about 10k xp in total each) But for the Scarab and MK60 there is little muzzle flash so it's better not to have a Red Dot sight as I can aim perfectly well without them and it doesn't reduce mobility nor visibility. I can see more of what's going on around me with ironsights. Plus it feels as though it differentiates the weapon's if they're not all looking the same with Red Dot sight's.

I would have a Red Dot sight on the Feline as well, because although the ironsights are manageable they're unreliable and you don't want to miss much with it's high rate of fire and they small amount of ammo you're given. I also find it more difficult to find more ammo on the ground for Feline so I always tend to pick up someone else's weapon after 4-5 kills. So stick with the Red Dot sight.

Quick tip: If you're using a SCAR or Scarab then when you kill someone then pick up their SCAR or Scarab as a secondary and you get 240 ammo plus whatever is currently in your clip. You can go for days with that much ammo.

I prefer the iron sights for all weapons. I'm not really bothered with the muzzle flashes.

I like that the color of the glowing parts of the iron sights change when you use a different skin.

I liked Iron Sight because it gave me enough zoom and accuracy to get my opponents. But I soon found that my opponent and the maps blurred together a bit when the moved like head-less chickens so I use the red dot now to improve my accuracy.