Starscream is an exceptional air commander and should be in charge of the Decepticons. Just because Megatron is more popular doesn't deter Starscream from trying to weasel his way into the top spot. Although it is kind of hard to gain favor with the other Decepticons when Megatron continuously puts him in his place... 

While Optimus Prime has the most iconic voice out of any Transformers character, Starscream is a close second. There have been so many different variations of the Starscream voice over the years, and nearly all of them have been brilliant. The only requirements are a high-pitched voice with enough sleaze and schemeyness that it'd make unscrupulous lawyers feel uncomfortable.