BT-023GTs are discontinued, so any '23s you find are NOS. The replacement is the T-30GT.
Personally, I like the Bridgestones. But... I've never tried others. For my riding, I tend to go by the tenet "if it ain't broke, don't fix it". It doesn't help that the Michelins are about $75 a pair more than the T-30s. The Pirelli Angel GT's similarly more expensive.
I typically get about 7k miles on both ends, although.... my current rear is a non-GT T30, because the half-wit at CycleGear said on the phone that the tire she had was a GT, but it wasn't. I needed it sooner than later, so I took it. We'll see how long it lasts.