I had a chance to evaluate SyncFusion in 2008. Although it has the richest feature set among WPF charts I evaluated, my first impression was poor documentation. The help file has almost nothing. I take me awhile to get zoom feature to work. In fact, I had to go to support forum to get help.
Comparing to Infragistics chart, SyncFusion look is not as good. But it does have better feature set. Context menu and zoom is definitely a plus. In fact, it is the only WPF chart component offered zooming feature at the time I evaluated.
Royalty-free licensing is also a plus.