On the whole, I think that computer science has the greater potential for very high salary. However, you should realize that both areas offer the ability for a very good salary. The only difference being that there are many more jobs in the high tech world for CS majors that are far above that norm.
Therefore, while the overall odds of getting a very high paying job in CS is greater than in ME, you should recognize that these very high paying jobs are out of the norm and you should not think that this is an automatic.
The other thing to really take into consideration is where you live. Some skills and experience is highly coveted in some locations, but not sought after in others. Therefore, you should talk to some people who know your local market before going forward in either direction.
Hope that helps you in your decision.