I would recommend completing the main quest. It has no effect on your ability to play the game, and gives you access to Dragonrend and Call Dragon
Dragonrend- Literally physically forces a dragon to land, and has a really quick recharge (combined with the amulet of Talos) makes wrecking any level of dragon easy.
Call Dragon- Does exactly what it says, calls a dragon to fight for you. The only problem is that if your dragon kills the opposing dragon, you don't get its soul, so you have to perform the kill shot.
On top of that, there are tons of little intricacies and subtle things that you can only get from the main quest, and they're sooo worth it.
Also: 8 more levels (which is to say about 100 more iron daggers forged inexpicably) in smithing and I'll be making my own full dragonscale and dragon plate armor. This is my excited face!
Sig courtesy of that photo-matic magician limba
I went out the way that I fight. I went out on my shield. That’s it. Done. --Chuck Liddell
My goal is to end my opponent --Carlos Condit