In a perfect world - one in which there is enough viable competition to walk away from and return to the WWE machine unscathed - Randy Orton would occupy the upper reaches of this list. The man is as overexposed as a teenage MySpace profile picture, but neither the drive nor the rationale for his departure exists. He's comfortable in WWE, and WWE is comfortable with him; as long as he remains loyal and in peak physical condition - maddeningly, his methodical ring style has guaranteed five more years of Viper rule, at least - he is not going anywhere.
It isn't a perfect world. WWE has their guys, irrespective of whether or not the fandom shares the "high", and those who do not fit within that mould must get over through sheer attrition or serendipity. And, even then, we're afraid we have some Bad News; there is an incorrect way of getting over, and it is a punishable offence.
Neville, grasping the futility of it all, is desperate to leave. Austin Aries appeared to encourage this over the weekend, when he tweeted his excitement over earning more money than his WWE downside with fewer upcoming Independent dates. Though his recent WWE experience doubtlessly allowed him to hike his price through the value of novelty and increased visibility, there is genuine earning potential outside of the WWE bubble in 2017.
That, and the elusive creative freedom with which to prove you are as good as you say you are...