I'm inclined to say at this point that the character with the most available tools is the highest tier in this game.
Even without knowing each individual character, by looking at how the game works I'm willing to say that Lei is in a broad top five, in a narrower top three and I'll risk that she's second only to Jann Lee but this is just one of many opinions on the game.
The previous assessment of tools, opinions that she only suffers on long range and that she needs to be more careful with parries against throwers, coupled with my recent overview of the game through several mediums makes me say that I wholly agree with the opinion above that states that Lei can be played in different ways. And she should be.