Well, there is no Trial Version of Wings3D.... it's free, so you get what you get. It's based off of an older program called Nendo (it was used to do many of the art components for games such as Final Fantasy 7). One really important thing to note is that Wings3D does NOT support animation. So if you were looking to animate anything you do, it's not the program for you. That being said, while Wings3D is not very precise it's great for organic subjects.
Milkshape 3D is in the same boat, it's designed for the low poly era. It does however allow for animation. I would place it's complexity level at higher than Wings3D (which is pretty intuitive).
I would consider using Blender though, it's free and allows for a lot more options than either of the two. It takes a bit more to get going but once you learn the workflow you'll get the hang of things pretty quickly. Just prepare to find a hot-key sheet to print out or memorize them.