Truly depends on how you are going to use the boat.
Do YOU ski, one or two ski's, kids tubing, fishing....

I had a 19 foot galaxy with a 3.0. I slalom ski and the boat could barely
get me out of the water. I had to put a smaller pitch prop on it so that it
could pull me out - that killed my top end. Flat out it would only go 35
mph.

I bought a 19 foot Chaparral with a 4.3 this is a good all around boat. It
can pull me up on one ski and still has a top end around 50. We can pull
kids on tubes all day on a tank of gas.
I would go for a 4.3 with fuel injection. They cost a little more but you
get more HP and better gas mileage.

Stay away from the 3.0 unless all you ever plan on doing is pulling kids on
a tube and a little fishing.