How heavy a wetter do you have?
No matter your answer, I'd still suggest 4x8x4 premiums, unbleached.
* 4x8x4 because more absorbency is better (at least for us). And ds can still wet through one of those in 5 seconds if he wants. He can wet through a premium prefold with 8 layers of hemp fleece in his wet zone in less than 5 minutes.
* Premiums because they're a little bigger than the regulars, and yes, your babe will eventually grow into them. Besides, I find I need as much width as possible on prefolds, and have been folding down the front for a shorter rise and extra absorbency in the front for ds.
* Unbleached because they help hide bf poo stains, and they wash up super soft. Besides, if you sun or line dry your diapers much, the sun'll bleach them anyway, but without harsh chemicals.
Lanna