It's not a matter of which way has less trolls, but a matter of what kind are least annoying.
Everyone has probably experienced the new champ select, or at least heard of it. Riot's way of encouraging effective communication, teamwork, and less time to start playing. I have heard so many people complaining about how the new champ select "creates more trolls", and the like. However, no matter how "good" something may be, there's always someone out there to screw things up.
#And in this case, in terms of champ select, there's always going to be trolls no matter what.
Old champ select already has all those "captain trolls" where one person handles all the bans, which also meant if that one person is a troll he will ban things that you don't want to get banned, such as things you want to play. It's been there since the beginning of time, but with the new champ select, that banning power is now spread to 3 people, meaning one single troll can't just hog all the power anymore.
##"But the new pick intent would encourage more trolling!"
It does, but instead of 3 people getting trolled, only one is, and you would rather have one person getting screwed over, instead of 3. It's just like how shit works ingame, it is better to have one person dead and win the teamfight, instead of having 3 people dead after winning a teamfight.
##"But I called mid, and that 'support' took mid from me! See, having to pick TWO roles screws up everything!"
Yes, but it still isn't news, people sometimes don't even read the chat (purposely or just due to technical difficulties) and takes someone's role anyways after they called. But think about it, have you ever seen those days where there's at least 2 support mains fighting over for support, and results in a loss anyways? The new champ select decreases the chances of that happening. Or what about that one day you are out of time from trying to type and ask things in chat because say, your chat bugged, and took a role accidentally due to lack of effective communication? The new champ select clarifies where people are going, though not all the time, but it decreases the chances of that kind of miscommunication.
Yes, you have heard me. New champ select will have trolls anyways, but different types, and hopefully something that isn't as bad to face. Now people need to just calm down, and stop assuming that the new champ select will "remove" trolls; no, it doesn't. Thank you for wasting your time reading and happy picking!
#TL;DR: New champ select doesn't necessarily reduce trolling, but rather creates kinds of trolls that are not as bad to deal with.
######Though one last request, where is that report button for champ select?