my question is should I use the black or just the splash?
What results do you want? That can help you figure out which rooster is best.
i have both a black/white houdan and a nearly pure black both roosters
Can you post pictures of your roosters? That would make it easier to predict what color the chicks will be. There are quite a few sets of genes that can make a chicken black/white in color, and several other sets of genes that can make a chicken nearly black.
From what you said, and what I know of the Houdan breed, I think you will most likely get the same colors of chicks from either rooster, if you are breeding them with Barred Rock hens. Daughters will be black, sons will be barred (black with white barring, like what Barred Rock hens have.)
Regarding other traits:
All chicks will probably have a crest, but it will probably be a smaller crest than what their Houdan father has.
Chicks will probably show beards if the Houdans have beards, but there may be a few chicks without beards.
Combs will probably look similar to the Houdan combs, but may be a bit bigger or differently shaped.
Body size and shape will probably be somewhere between the size & shape of the parents bodies.
Daughters will probably lay eggs that are a lighter color than what their Barred Rock mothers laid, but the eggs may not be actually white.
