I've used MS Project. I haven't used Primavera Contractor, but I have used Primavera Project Planner (P3). P3 is a very powerful, very good piece of software and, while it can be used on small projects, it is best suited for really big projects. P3 is also quite expensive. Primavera has a good reputation, and I would personally feel confident that they would have a good product in "Contractor". My own experience with MS Project is that it is not bad for setting up a schedule, it has nice graphics, and is reasonably priced. However, when it comes to updating the schedule, the program tends to fall short.
If I may offer some free advice (advice being worth what you pay for it), no matter which scheduling software you wind up using, NEVER use forced dates, such as, must start on....., must finish on....., etc. Let the software figure out when things can be done.
Hope this helps,
It's always easier to get forgiveness than it is to get permission.