You can't go wrong with SENuke X or Ultimate Demon. They both offer a ton of different uses and support a ton of different platforms.
Stay away from Scrapebox, you can't do much more than spam with that thing.
I would go with scrapebox. It's a really SEO swiss knife. You can do a lot of things with scrapebox not only post comments.
SEnuke X and scrapbox
SENUKEX, SCRAPEBOX,AUTO LINK BOMBER, XRUMER and much more