I own the 157 Banana Magic, but I do zero park stuff. I might go in there this year with my son and I wouldn't consider the Magic a good dedicated park board, but I have seen an amazing rider in the park on one, and he ripped on it. I know my local Lib Tech shop owner wanted to get a Banana Magic and he is another great park rider as well as and over all excellent all mountain and big air rider.
In the widwest, if you don't get much deep snow (I don't know what your conditions are first hand) I think you could get away with either the 157 or the 154. The 157 is a touch longer than my old 159 and rides solid on the hard pack.
I weight 175 with out gear. If I wanted a more playful length for jibs I would personally go with the 154, but I wanted more deep snow/powder float and have a 159. I had it in 14"-24" of light powder yesterday and I'm actually surprised at how well it floats. I think this is due to the pronounced nose kick and the rocker or 'banana' that the board has. If you don't get as much deep in your area, you might be happy with the float of the 154. I haven't ridden one but it might be enough float for me and I wouldn't know.
The Magic is a carving machine. If you like to carve and haul butt, this board is a good time. It has Lib's tightest side cut and feels like it can carve circles.
I know that my local shop owner went to order a 157 and the factory is out of them. Now he can't get one directly and he is going with the T.Rice with the powder nose as a second choice. If you decide you want the Magic, I wouldn't wait too long to pick one up so you make sure you get one.