Notice Leo is the second favorite though for the same reason I stated regarding Don. A certain sub-section of fans chose Leo because they realize everyone chooses Don because he is the most underrated but in reality he is overrated as a result. So they go for the next most underrated turtle which is Leo. However this makes Leo the next most overrated one behind Don.
Notice how the turtles that have gotten the most attention throughout their history (Mike and Raph) are the least favorites. No one wants to choose what the franchise sells as the most popular, so in order to counter this, they gravitate towards the other turtles. However, in reality, they gravitate towards the most overrated turtles, Leo and Don.
Basically, choosing Don is cliche. Smart people choose Leo as a result, but he is ultimately not any better. This makes Mike and Raph the correct choice, however, the franchise wants you to love Raph the most because come on, they always sell him as the main turtle despite Leo being the supposed lead. So ultimately, Mike is the best choice.
So like Leo the most, though.