I always thought it was Don for 2 and Mike for 3...and yeah, this is going to be Leo's spotlight I think.
The storyline for the new movie has Splinter sending him to round up his brothers after they have gone their separate ways.
*sigh* I personally feel that Leo gets WAY too much attention. It is not "the amazing adventures of Leonardo, and those other guys"...its TMNT...ALL of them. No one should get top billing among the four