For resale and long term proven reliability I would choose Yamaha. I’m off to the kitchen now to put the popcorn on  

 Yama ha ha ha, you'll be laughing with the reliability and resale.

 Longest warranty and price, including fitup.

 Lots of elements to consider when choosing a motor. Comparing those two on weight, power, and displacement I'd say the merc has it won. They have a great following over in the US and have been proven as a good design. Nothing wrong with either in my opinion, get the one with the best price, warranty and local service support. When something goes wrong you want it fixed fast with a smile.

 You cant go wrong either way.The merc 150 gets very good reviews.Having said the yamaha 150 is proven over many year to be extremely reliable.

Come resale time you wont have a issue moving the yamaha but there is still the black anchor brigade who will avoid a mercury.

 I have a pair of yamaha F150's on my rig. I think they are a little noisy, bit behind on the latest tech and a bit thirsty. 
But I'm over 1500 hours and they keep on ticking over every time I turn the key so I'll live with that. 

 is a black anchor is pig ignorant and utterly clueless. But hey, they are still out there,  I guess. The Merc is a newer, simple design, easy to service, been out since 2012, no known issues. 20kg less than the Yamaha, bigger displacement, more grunt at the prop. You won't go wrong with either. I only have 675 hrs on mine in under 3 years, this year has slowed me down a bit. Zero problems, pushes a heavily loaded Reefrunner along at 1.2 l per NM at any speed between 20 and 26 knots, 3800-4500 rpm --that's a boat which weighs 2 tonne in the water fully fuelled NM. Can get down to 1l/ nm  if I want to drive at 3600 rpm/18 knots. Stuff that, lifes' too short. For those who want to deal in Km, which you never should on the water, 1l/nm= 1l per 1.852km, 

Some actual screenshots from a cruise on an admittedly pretty calm Exmouth Gulf.

The last one is the only reason I would want a 200hp Merc on the back instead--to be able to do 30 knot cruise on a glass calm at 1000rpm under, rather than 500rpm under.  But again, you won't go wrong with either.

 At this stage im definlaly looking to go withe Mercury 150. Lighter, more grunt, quieter, easier to service six year waranty.