Donna Vincent wrote:
A reviewer on the Joomla extensions directory says JomComment has very bloated code that substantially increases bandwidth.
Well I have not tried it that much, and haven't looked into the code really.
But I would still recomend it as number 1 comment system due to these to me important facts:
1 - It's cheap
2 - Support is outstanding (Just a Skype call away)
3 - It installs and performs perfect out of the box
4 - It looks good even with the default templates
5 - I like the fact that it's AJAX powered so comments are instantly added
6 - I have used comment systems and guestbooks without the "Type these letters" security and it got bloated, slow and filled with Viagra spam within a few days - not have 1 spam comment so far 
7 - Nice with the built in global avatar standard
That's enough for me really...