I had the left eye done first, and the right one done 2 1/2 weeks later with Zyoptix. I'd done loads of research about it and where was best, and there was only one place really that had a perfect score from this forum - The Centre For Sight with Mr Daya.
The reason that I went for Zyoptix was that it tends to produce a better night vision result compared to the standard LASIK, and this was a high priority for me. My higher order abberrations also were border line for zyoptix which swung it for me.
Initially there are halo's around lights at night, but they have faded quite markedly after 3 weeks (it takes about 6 weeks to settle) in the left eye, so I'm just waiting for the right eye to follow.
Apart from that, the result is pretty amazing as I now have the same vision that I had corrected beforehand - 20/12 left and 20/10 right, which seems to be one of the best results they've had to date.
Needless to say, Mr Daya and his team are very competent, and they produce very good results consistently, and safely.
Can't recommend them enough.