I made a list of who the top 100 players use the most as a part of their Defense Team:
(as of 22.4.2018 at 13:00 cet)
Please note that top 15 most popular choices includes exactly 3 heroes from each element.
And top 10 includes exactly 2 heroes from each element.
Another interesting fact is, that there are 7 HoTMs and 7 regular legendary heroes + 1 spec.event hero.
Other popular choices: