After we released AceSEF most of users comes asking why we needed to develop a new SEF component, there are just great SEF components avaliable. Well, yes there are SEF components but they either JUST generates SEF URLs (sh404SEF) OR doesnt fullfil the needs (JoomSEF).
Here it is the comparison table of the most used sh404SEF and JoomSEF components versus AceSEF component.

	sh404SEF	JoomSEF	AceSEF
Free Version
Free Support
Generates SEF URLs
Easy-to-use graphical user interface	Worst	Good	Best
Written according Joomla! 1.5 Framework & MVC Standarts
Written 100% in modular way
3rd Party extensions installation and management
Sitemap (XML) for ALL components
Meta Menager in batch mode
Advanced SEF URL rewriting methods management
Basic SEF URL rewriting, no plugin obligation to make SEF
Supports Joomla! 1.5 router.php files	Paid ver.
100% accurated pagination
Alias option for ALL components
Managed automatic meta tags generation
Duplicated URLs management	Hard-to-use	Good	Easy-to-use
Unique numerical URLs for duplicated URLs
Advances SEF URLs filtration in backend
Migration from other SEF components without losing old URLs
Automatic update(new version) checker
Upgrade page
Customisable 404 page
Supports Google News numbering	Simple	Extended	Extended
Queries for FrontPage (cache on)	24	27	31
Redirect from non-SEF to SEF URL