155 Wide is a great size for you. Honestly, a 159 is too big for you. Unless you have an exceptionally wide stance, your height won't matter. It's your weight and boot size that play the biggest roles. At only 155lbs, a 159 is almost a powder board size for you. You could even go 154Wide if the stance allows it. For park boards, you want a softer flexing board that is also on the shorter side.
Brands to look at:
Lib Tech: Skate Banana, Skunk Ape BTX, Dark Series C2 BTX
GNU: Park Pickle, Carbon Credit BTX
Ride: Machete, DH2
Burton: Custom V-Rocker, Easy Livin Flying-V, Love
K2: ParkStar, DarkStar, World Wide Weapon Rocker
We only have these two boards in your size, but a great deal.
My favorite out of all of the above would have to be the Ride Machete. That board plain rips. Freestyle board, but it also dominates all-mountain.
NeverSummer is also a highly regarded brand, but you'll have to have others chime in on this one since I have never set foot on one.