I've heard many people say how good their first one was and their second was shocking! and vice versa so you can't be guaranteed another 'good' one.

My DD is a 'good' baby. Sits and plays happily by herself, slept through at 4 months, great with routines, good day sleeps, not too much of a fussy eater etc. Given that I still think that not all are the same so having a 'good' baby does not make me want another (But she has many health problems which hopefully will work out in time. This has definitely put me off having more!!!)