I disagree with both of you.
When you just want to play for fun, you dont play ranked. That is the #1 rule of LoL.
Ranked matches are for people who want to show what they are capable of, not for people who just want to have fun.
Duo-Q is not bad, but do it with the good reasons.
Play Duo-Q with your friends and not with people you just met.
Do it with people with similar skill level who have proven to be equally as much driven as you are. That is what Duo-Q is for.
Ranked Teams is when you want to play seriously with 5 players.