I use the Korg TM-40, which also includes a really good metronome. The tuner has an LCD display, which looks like an analog needle, and refreshes quickly. I don't really notice much lag at all. In addition the the needle, there are three lights indicating tuning as well. If you hit the note dead on, the center green light comes on. A little flat, and the green and a red light to the left come on. A little sharp, and the center green and a red light to right come on. If you get too sharp or flat, only the red light displays.
The benefit of the lights is that you can spot check your tuning while playing by glancing at colored lights out of the corner of your eye, keeping your main focus on the sheet music.
The unit is pretty tough. It's fallen a couple of times off the music stand and hasn't died. Also, the metronome and tuner can be used simultaneously. I think it costs about $30 most places.