There are many types of blankets to consider so be aware of what its purpose is. Is it a stable blanket, intended for in-barn use only, a light, medium, or heavy weight rug for outdoors, do you need to buy a full hood or neck cover? All good questions and things to consider. What is your price range-=now there is huge variance in this. Not all blankets are created equal but I don't believe you need to spend a million bucks either. I prefer Weatherbeeta but have had great luck with Rider's International as well. but you decide for yourself what brand suits your horse best.
Fitting the blanket is vitally important. A blanket that is too large or small can cause terrible rubbing on our horse making the experience far worse than leaving ell enough alone and not blanketing at all.
From Dover Saddlery:
increments, so choose the closest size available.
So, to blanket or not that is the question to you all, what do you do?
Here are some articles on the subject:
To Blanket or Not to Blanket by Cherry Hill
Why Not All Equines Need a Horse Blanket
To Blanket or Not to Blanket? By Horse.com