I have a number of PAR20 lamps. Currently, I have halogen, CFL, and LED bulbs in close proximity, so I can readily make comparisons. Of the three, I like the light of the LED's the best. As the other bulbs burn out, I am replacing them with the LED. The LED I am using is the FEIT 5K bulb. I prefer the whiter light.
The reason I have all three types up is that they were all originally halogen. I wanted to replace them with something more energy efficient for a long time. My fixtures have a trim ring that snaps onto the bulb, so I needed true PAR20 shape and size. It was only a couple of years ago that I found a CFL that would (mostly) fit properly. And it was only last year that I found a PAR 20 LED that had true PAR 20 dimensions, and had a reasonable output (500 lumens).