R63
R63 is easy to managed, It's less buggy, stable, no disconnections, source code is neat, dno what else. R63B
When it comes to R63B, you'd need to edit the source to fix errors, You'll need to FIX all errors according to the error logs. Also R63B has Groups, Profiles, more commands, and stuff like that.
I don't know what else to put in (I know it's not enough imformation.)