She is the highest ranking contestant because she made it to the Final Three, regularly, more than once. By regularly, she made it there without returning to the show, unlike Owen in TDA.

My favorite out of these is actually Izzy, but I think Heather has a lot of complexity. In season 1 she was a great villain in her own way, in season 2 the other contestants knew she was evil and shunned her, in season 3 she triumphantly wins which is an amazing twist.

Yeah, out of these Izzy is my favourite :) If it had some of the other contestants I wouldn't know who to choose.

everyone used to hate heather. what happened?

People favored her over Alejandro in the TDWT Finale. In fact, they cheered when Heather won pover him.

I actually wanted Alejandro to win; I wanted to DIE when Heather won!! T_T

You forgot Ezekiel but Izzy is my 2nd fave contestant and is my 3rd fave overall (eva never competed in tdwt ):

Noah and Geoff were in RR, so they're also three season contestants.