articlepool.com/distribution

# Fully unlimited distribution starting at $18/month!
# distribution to 1000+ real, not spam, qualified article sites.
# User friendly, fully automation system.
# Powerful tools to prevent dublicate content!
# Real time monitoring and reports.
# Setting tasks due to future.
# Wide range of categories.
# article marketting experience since 2005!

iSnare.com

# $59.50/month limit of 10 per day.
# distribution to 400-500 sites.

thephantomwriters.com

# $140.00/month limit of 4 ezines.
# distribution to 420 sites.

articlemarketer.com

# $22.50/month unlimited.
# distribution to 600 sites.
# Wide range of categories.
# distribution report.

articlessubmissionservice.com

# Offers only manual distribution
# Starting from 8$ for each article.
# distribution to 500+ sites.
# 2-3 days turnaround time.
# Bonuses worth of 30-40$.
(Suggested for manual preference)

Conclusion
My final nominations are articlepool.com and articlemarketer.com.

But articlepool.com is really impressive. I have tried them for 1 month and happy with them.