Sacred Haven of Debauchery

It takes longer to level up archery, the blacksmith, and get a crossbow than it does to complete a bit of the main quest and learn the Shout.
Kosh, let's play Dawnguard; add us as friends, and we'll give you some Dawnguard armor. And yes, there are no horses there, but you can ride Cyclops.

But I learned the Shout later. In general, I ignored the main quest for a while, somewhere around level 80-100, because there was a lot of interesting stuff to do in the game even without it.

Added 2 minutes later
I'm saying that by the time I learned the Dragonrend Shout, I already had everything. By the way, I could easily kill dragons even with a simple bow, considering they often get distracted by companions. And when you have Serana and another companion, let them fly as much as they want; I'll still take them down.