High Feral Dragon(which was the 3rd heroic I got): It does look amazing and it would on a tie with the High Supremacy Dragon(which I don't even have)
Supersonic Dragon: probably one of my first legendary(in rarity not in element) dragons that I got, still it's very solid.
High Resolution Dragon: The first heroic I got, looks amazing, very retro game themed and would be in a tie with the High Score Dragon(also I don't have because I didn't reach lap 15 on the High Score race and didn't end on 1st place but still I got the High Amuka since I reached at least lap 12 on that race).
Silly Dragon: looks very funny
Pure Flame Dragon: I do remember yet the days when pure had no weaknesses and I remember that I got my Pure Flame Dragon(back between mid 2015 or mid 2016) by breeding Ivory or Pure Terra(which I got if I remember by breeding Ivory Dragon(which I got from free cards back in 2015 on the pc version of Dragon City and I could get some pures because they weren't locked during that time) with a Terra Dragon) with a flame dragon.