I do believe Modern having the anti-bot measures is the best option mainly because newer players will mostly be going to play Modern and having people win more in Modern would directly encourage more players to play in the long run. We don't want the "entry" mode to be the hard mode in games.
Botting already has minimal entry right now w/ all the cheap cards available to be used in Modern so once botting moves to Wild they'll need to rent a lot more cards to farm the next reward sets more effectively which in turn would get exponentially more expensive for them to do so with each new set launched which could discourage those who don't own much of the cards to still bot in Wild.