Well I haven't read a whole lot of the Mirage series, yet (they're coming hopefully!
). But from what I have seen or read the first movie is probably my favorite. The reason being is that it was a great combination of the original Mirage concept and the cartoon. The movie adopted a good deal of the plot points from the comics, and to an extent kept the grittiness of the original turtles. At the same time, they made it light hearted like the cartoon so it would also be enjoyable to those that only know of the cartoon. The movie pretty much became the best of both worlds.