If you want to get legendary or high in rankings it doesn’t matter what decks are u using, the only thing that count is to invest plenty of your time in the game, and by plenty i mean lots of hours every day.
I don’t know if investing lots of money helps as well, not from my experience, as i’m playing the game for more then 2 years and invested in few expansions but only got legendary once even though i always have the top 6-7 decks.
I would suggest to play the game for fun in spare time, not investing any cash in it!!