Which one is easier to build in
Scream Machines
does each let you build in terrain
yes
which one has the most roller coaster choices?
Scream Machines by far
SM has a more advanced editor in my opinion, tons more track options. Tons more train options. Real time g force calculator in the editor, nig plus for that. Graphics in SM are way better if you use a good environment which there are many available. NL, looks good and works good and is relatively easy to build in as well but lacks many things which SM has. both allow you to import 3d objects, Only SM allows you to import custom train models. Scream Machines is a lot more easier to deal with game problems, if any. You don't have to visit so and so site because so and so person made this for the game. Just one direct site. Their staff is extremely quick on technicalk support over on their forum, nl has no forums for help, just e-mail and sometimes takes a bit for a reply. Updates for all parts of SM are released on the official site, NL sometimes has updates, such as the terraformer which you literally have to hunt for to find at times. I had to hunt for a terraformer update which was never announced over at
www.nolimitscoaster.de
I recommend Scream Machines over NL simply because it has more features and you can get technical support faster.