My preference is the ABR-1 bridge. The original design works quite well and has that 'classic' look IMHO. You do need to have properly fitting/functioning saddles though. Gibson's lack of quality control for the holes that are machined into the brass saddles is a problem. Sometimes the hole is drilled too high, sometimes the hole is drilled too too low.
You can either be lucky and start out with good saddles (I never have been lucky) or you go through a lot of Gibson saddles and pick out the good ones or you use a quality third party, aftermarket source (e.g. Pigtail, etc) to get good ones.
I posted this saddle note recently in another thread:
"... Many of the saddles have misaligned adjust screw holes. Hole too high and the screw rises up off the bridge and saddle binds. Too low and vibration energy is focused through screw shaft and saddles rock side to side.
What you want are saddles that lie flat on top of the bridge and adjuster screw shaft that neither rises nor bottoms out throughout the entire range of adjustment.
I have seen lots of bridges with some of the saddles with the 'hole too high' error - Gibson's process somehow results in banging them flat = bent adjuster screws that don't work. For want of a properly made inexpensive part, the performance of a multi-thousand $$ guitar is compromised."
At this point I'm very sceptical about differences in sound... specially in a live situation. Tone is subjetive.
But, from a mechanical point of view, the nashville is superior. More stability, stronger, "cleaner" in its height adjustments, no buzzz and more intonable.
Actually it looks stronger, but its not the majority of the nashvilles I have had on various guitars have collapsed. The Nashville on my first les paul cracked in half within 4 years, a recent gotoh nashville I had on my #1 es-335 collapsed after about two years. The original abr-1 on my 67 es-335 shows no deterioration. The problem is that while the abr-1 is solid on the bottom, a Nashville is not, it is actually hollow or more accurately ladder shaped. Additionally if you remove your strings and bridge and touch the nashville stud (pardon MY french!) it wobbles. It doesn't sit tightly in its threads. I do get a great sound from simply reaming an abr-1 to fit the Nashville studs but on three guitars I have taken the plunge and dowelled the Nashville anchor holes and properly installed an abr-1 and the results are fantastic. What the nashville does for gibson is give it some manufacturing leeway in setting the neck and installing the bridge posts thanks to the extended saddle throw. But an abr-1 equipped guitar is a little bit twangy, not like a tele but just enough to give note a bit of extra envelope and piano tone on the wound strings. Its only drawbacks are intonation drift and the retaining wire rattle, but to me the improvement is so vast that I manage that, checking my intonation more frequently and such.