I would vote for the 8600 if I were choosing one now. I know people with both and I've gotten to play around with both, and I say the 8600 for several reasons. The 8600 has Celltop which I loved playing around with for a few minutes. Sports scores and weather with only using airtime. I also liked the design of the 8600 a little better. Maybe it's just because I see so many people with a Razr but the 8600 looked similar but maybe a newer, better design. The LG format also impressed me in its simplicity because I'd never used one before. In the phone book, it was really nice how I could assign a single name multiple phone numbers for home, cell, work, etc. The reception seems about similar. Some people online even claim the 8600 is a tad better but I haven't directly compared them to make an opinion myself. But on the moto I do like the fact that I can switch my phone to vibrate without having to flip it open. But to me at least, the 8600 seems like the new toy on the block that I would go with.
I just bought the AX8600 a month ago and love it. I haven't had a problem with signal or battery life. The set up is really easy to learn and get used to. All of my friends own the Razr and they all are jealous of my 8600. I use it as an MP3 player when I go on walks. The only thing I would change about that would be adding the ability to use the bluetooth headset to listen to the music. But you can't have everything. The front buttons on the face of the phone for the MP3 player is a nice touch and I like being able to set a different wallpaper for the main screen and the front screen. Reading text messages from the front screen is also a real treat. You don't have to open the phone to read new messages. I know some of these aren't big issues for all, but I really enjoy them.
I was checking out my friends 8600 at a bar and made a call and had very good reception and overall really liked the phone. About a year ago I had to make a call from the same bar w/ a razr and wasnt to happy with the quality. Maybe he had the volume way down or something but I liked the 8600 better. Lots a complaints about receprtion w/ the razr go w/ the 8600