It comes down to whether you want a topmount, drop through, or drop deck. The Supermodel is definitely one of my favorite boards of all time. The concave is great, the construction is super durable, and the specs are pretty much perfect (IMO). The only benefit of the Nemesis would be that the foot pockets created by the drops are nice for locking your feet in.
Topmounts are pretty awesome too if you want a more controlled slide. The TuTone Tagilo is an awesome topmount for sliding and such.
Actually, I had taken comparison pics of my Nemesis and Supermodel months ago, and I just found them on my phone.
http://i828.photobucket.com/albums/z...-48-24_788.jpg
http://i828.photobucket.com/albums/z...-48-43_124.jpg
http://i828.photobucket.com/albums/z...-51-37_753.jpg
http://i828.photobucket.com/albums/z...-49-39_679.jpg