Just did my fall (once a year change), filling with Castrol Syntec 10W40. I drive 2500-3000 miles annually; May to November (stored during winter months).
As Mike stated, there is no "easy" answer...only you can make an educated decision by reading the pros and cons listed in the various posts or go to
www.lnengineering.com and read everything you ever wanted to know about motor oils and more. I just know the experts do not recommend Mobil 1 0W40 and many other 5W or 10W40 brands should work fine for your climate and driving habits.