When comparing SnagIt to other screen capture applications, I would suggest adding some features that SnagIt is lacking.
1. A pixel ruler would be exceptionally helpful.
2. The ability to sample a color and get the html or rgb formula would be helpful (aside from hovering around with a temporary formula pop-up with the dropper tool).
3. Also, might I suggest the ability to manipulate the angle of a shape/line by typing in coordinates.
4. Multi-color fill with a gradient option
5. A birds eye view tool that would enable the user to select a portion of the capture and show it in a zoomed view on top of the original layer.
6. The ability to apply a filter to the capture (e.g., preset tones, 3D manipulation, shadow of shape relating to a designated reference point).
7. The ability to add text to a shape/arrow/line without the second step of adding a textbox.
PicPick recently added several features to their application that are highly useful that you might consider implementing as well.