first off what kind of boat yo
first off what kind of boat you are you going to be using the motor on. you said you were going to a new motor or a newer used motor??? 2 stroke are great for hi torque 4 strokes are great on gas but weigh alot more and need more looking after i have both mer 50 4 stroke efion my tracker tx185 so far i have only filled it up one time this summer fishing every saturday on the flip side i have a e rude 25 2 stroke i river fish with on a 16' jon boat it will use 6 gals in a weekend on the river fishing it does about the same as the tracker as for speed but weigh of the jon is half of the tracker e tec makes a great 2 stroke and merc makes a super 4 stroke these are what i use and work on maybe other folks will add some to this post
i hope it helps
jr