Here's a great Laravel package if you want to use the no CAPTCHA reCATCHA that was introduced by Google last week:

https://github.com/anhskohbo/no-captcha

Personally I'd go for a honeypot before resorting to a recaptcha because a honeypot is invisible for users. Here's a good package by Maksim Surguy if you want to go that route:

https://github.com/msurguy/Honeypot