Most of the top options have free trials including:
Writer’s Duet
http://writerduet.com
Has definitely gained popularity in the industry. Cloud-based so it’s terrific for collaborative efforts and easy access. The free version gives you the ability to do create 3 projects (but without collaborative tools). If you are interested in a full 30-day trial, contact me for the code.

Final Draft
http://finaldraft.com
The industry standard. Great for solo scripts, not so much for collaborative efforts.

Scrivener
http://literatureandlatte.com
Scrivener and yep! It has script templates. I would not recommend this software when you get ready to go pro. The pages are not at the correct 1 minute = 1 page length.

FadeIn Pro
http://fadeinpro.com
Gaining popularity in TV Writers Rooms across the industry.
