Sharpness in LCD displays isn't exactly an advantage. These displays are perfectly sharp by design; if one appears sharper, then either contrast has been cranked up or the sharper display has a thicker grid between the pixels. In a flat panel you want less sharpness, not more, at least if looking for an accurate image.
Looking at displays in a store won't get you far, unless it happens to specialize in professional graphics and offer a semi-darkened corner with roughly calibrated displays and test images.
Actually, the main reason LCD displays may appear differently sharp in a store is because stores used to, and most still do, drive them with a VGA splitter, which is basically a 5-channel analog amplifier that powers up the signal a bit and sends it to a lot of screens. Between analog output and a splitter built to a price point, the signal arrives degraded, and different displays may have different strength of sharpening to compensate for it. Since you're obviously going to use DVI (or DP) at home, it's of no relevance to practical use.
Other parameters - color accuracy and backlight uniformity - require testing in adequate conditions, preferably with equipment, not in a brightly lit store. You can buy a rotting lemon and think it a gold egg.
Better look for good reviews (done with a lot of numbers and their understanding) to see what's good and what is so-so. IPS displays generally tend to be better, but the bottom tier - which are not necessarily bottom priced - are no better than midrange TN, they basically *are* low-end TN with an IPS panel stuffed in, which does them no good other than riding on Apple's IPS-marketing wave.