triton x18 engines opinions.

[tennessee keith]

I am looking at a Triton x18 aluminum boat.
Opinions please, on outboard engines.
The price different from a Mercury 90hp to a 115hp is less than a $1000. In a package deal.
I like the 4 strokes that I've heard.

Questions
What hp would you recommend?
Mercury 90ELPT Optimax
Mercury 90 ELPT Four Stroke
Mercury 115ELPT Optimax
Mercury 115ELPT Pro XS Optimax
Mercury 115ELPT Four Stroke
Or any other.

Would the differences in hp be to my vantage?
Mostly looking for fuel efficiency.
Top speed is not that important. Give or take 10 mph differences.
Between to 90 hp and 115 hp. Both should run in the 40's mph.

Thanks for any info