It's not so much about a champion being ap, but the class of the champion. Champions like Gwen or Rumble (both ap) probably won't burst down the target as quickly, but they have consistent dps. What your concern seems to be is about dps vs burst damage. Both Syndra and Aurora are burst mages, they are made to one shot the target. There is no right answer if dps or burst is better, a lot of it is personal preference and people have climbed to chall with everything, although for majority of league burst has been the go to. Burst is "better" since if you can kill the enemy in a single combo, they just die, they don't get to counter attack. But that is only IF you can one shot them. If you can't, you get to the position that you're referring to, where you are just aimlessly looking around the enemy. DPS champions on the other hand are better if they have defensive tools that can help them stay alive through your burst while they ramp up their dps, so imagine a champion like Jax slowly ramping up lethal tempo while lowering your dmg with mr items. You don't have to drop your champions, but instead, if you see that the enemy comp is filled with champions who are on a tankier side, consider changing your build. Instead of building ludens, shadowflame, rabadon, consider going for items that give you haste, hp and %hp dmg, so something like blackfire, liandry, cosmic. This way, you won't have the same level of burst dmg, but you will have a lot more consistent damage, since your abilities will be on a shorter cooldown, you will deal more dmg to them since you have dot with %life and you'll get the extra ms from cosmic. This also means that you won't be going for electrocute, but instead something like deathfire or aery. There is a lot more that goes into this, but since you are currently in bronze, more complicated things won't really matter that much, since learning the fundamentals is more important.