Having spent my 3000 hours in Dota, my vote of course went for that. Back when i got started, I joined the GB guild and channel, and asked for people to play MM with. Nowadays I have ober 150 of these people on my friends list, and never play without a full 5stack. This way, you never get raged at and have a really fun time. If you decide to do the same, I can only recommend you stay far away from solo queuing, and instead ask around the channel for people to play with you, you will almost always find some on your skill level.