Need suggestions on synthetic oil!!!

[bmr]

Hey guys my car is due for service and I am trying to figure out if I should take it to the dealer or if I should put another oil that will be better for my car.

From what I have read 5W30 Amsoil, Royal Purple, and Red Line are good choices. I was starting to get convinced on Amsoil but then I read that someone posted that it is not an ester based oil (is this true?).

I also read that someone claimed if you dont use Nissan's ester oil the mpg and the horsepower of your engine will decrease. I would like something that would affect mpg and horsepower in a good way or not affect it at all. Also, I want something that will improve performance. I live in California so the weather is almost always hot and I dont do anything crazy driving like dragging or taking my car to the track. The most I do is some aggressive driving on the highway but still I wouldnt mind spending extra money on better oil for my car.

Also, please suggest what oil filter to use! Thanks a lot guys!