If you build it, why will they come?
Why do your players play? Why do they make the types of characters that they make? Why do they so often follow the same patterns and have those formulaic characters speak with the same voice, again and again? If you don’t believe that they are, you are not looking hard enough, or you never left kill-by-numbers dungeoneering.
Casting Shadows 
Although we have talked about this often in person, I will comment here for posterity’s sake.
I notice that I do tend to always take “the wizard” character, regardless of the setting: a “telepath” in Adventure!, is one example. Although, lately I have been trying to branch out more into “the fighter” characters, with limited success. In truth though, my failing in chargen is that I most often end up with a character that is a “jack of all trades and master of none”.
Self-examination reveals that this is probably because I want to keep my options open, not start out with someone over-powered, and enjoy the growth of the character, in whatever direction it grows. However, what it produces is a character that often can only scrape by a situation and at times, even requires rescue from a kindhearted GM. While that is challenging, it is not always as satisfying as being able to scoop up a great whopping handful of dice and rain holy hell down on some mope.
Jack-of-all-trades versus the One-trick Pony… now in smell-o-vision. This is often the debate, isn’t it?
I think this question is exacerbated by constantly shifting game systems and having to craft characters without knowing how each entry or skill will actually affect play, or how it will flavour, enhance, or limit a character.
In a new system, I tend to favour the pony, and use that over-blown skill to both carve a niche, and learn to assess relative skill levels. Subsequent characters in the same system will tend to be much more balanced toward a realistic assortment of skills and abilities, with a broader base from which to grow. I do not find the pony all that satisfying to play, so I try to generate personal interest in the character by devising a plausible but perhaps convoluted backstory to deal with how they got that way, and providing ways for the GM and myself to deal with this in play – should the story/setting allow for such.