solo/duo queue is where it's at to prove your worth.
Not really, you can either carry, be carried or lost games due to your team, exactly like in 3v3 and 5v5.
If Solo/DuoQ was the real deal, there won't be any LoL Teams and Tournaments would be about Teams made like in Solo/DuoQ, which is not the case. The deal is Ranked 5, but people like measuring their e-peens, thus, Solo/DuoQ gained a lot of importance because of that.
It does not matter what League you are in each different Q, if you are a good player, you will perform well, if you are not, you won't.
In any case, this is just my opinion, I am in no way saying Solo/DuoQ does not show a player's skill. I know the general believe is that the other Qs are "easier", but they actually are not. On the other hand, they are not harder either.