Will Wheaton, hands down. TNG could have benefitted without him.
I think Will Wheaton has gotten a really bad rap over the years. I personally don't feel like his acting ability had much of anything to do with why his character wasn't good. You see, I was 13 y/o (about year younger than Will) when TNG started in 1987, so one of my biggest pet peeves, particularly of that first season, was the demeaning and dismissive way the writers treated, not only Wesley Crusher, but children and teenagers in general. In the case of Wesley, you had this 14-15 y/o teenage actor playing the part, but they wrote the character as though it was for an 8 or 9 y/o, and that is exactly how all the other characters treated him. His was the most prominent example, but certainly not the only one. Consider the "children" in "Justice
". The Enterprise goes to this planet where its inhabitance are all about sex and "make love at the drop of a hat...ANY hat." as Tasha Yar put it, and yet all of the "children" (who in actuality all appeared to be between 15 and 17) act like a bunch of 50's, "Leave it to Beaver" innocent, naive 5 y/o's completely oblivious and disinterested in the fact that all of the adults are making out in plain sight all around them. Yah, that's