I have NB aio's, pockets and prefolds. I personally don't like the prefolds very much. My aio's are NB size but don't fit dd properly - they're tight round her belly and too loose round the legs - which is a shame as they are super cute- but I get too much leakage.
My fav is my pockets which are one size not NB and I just do them up on the smallest buttons and use two inserts for days and 3 for nights. No leaks no rash no night waking for wet nappies and 1 happy bub = a happy mum
I bought a variety before dd was born rather then stocking up on one type so I could wait and see what worked best for us.
DP prefers 'sposies but that's tough luck for him coz dd's bum hates them