After my supply of 1307s run out, I'm done with them. I'm going to use DS3231 moving forward.
I echo this. The ds3231 can use the 1307 library without modification so it's easy to use. I've had a 1307 project running since October and it's about 5 minutes off now. Another project with a 3231 has been on since mid December and is still within 1 second of my computer's clock.