Quoted from Mad_Dog_Coin_Op:
I have both LCD and LED also in my collection. I like the options the LCD gives you but hate the form factor. The height of the LCD can be seen from the player's perspective as a shadow in some instances. The LED is the footprint of the OEM display and looks much cleaner installed. The other benifit of the LED is lower power draw. My Shadow has Comet LEDs installed which are pretty bright. I feel the brightness and overall display color of the LED Color DMD is a better fit for my game (and a little cheaper).
I admit, the fit of the LED is great, I wish the LCD came in that size but the LCD works as intended even though it's bulky. I also agree about the power draw but the LCD is low too, nothing like the old DMD.
The other issue I had with the LED was the white light line reflection on the display, I tried electrical tape which helped but maybe I just did something wrong.
In my opinion, whichever one you choose is massive improvement in looks and power consumption over the DMD, the LED vs the LCD comes down to personal preference because both are great!