Four things to note:
1. I'm basing this ranking off of how they performed in the GROUP - not their solo careers.
2. They are all great rappers, making them hard to compare.
3. The "worst" Slaughterhouse member is still better than most rappers out there.
4. This is based on all of the material they released so far (cypher, hammer dance, session one, loud noises, 2.0 boys, and their late 2008/2009 stuff). Their album in June will probably change my rankings.
#4 Royce Da 59
He's definitely one of the best rappers in the game. As a solo artist, he is very talented and his chemistry with Eminem is not far short of flawless. Royce as a solo artist has some of the best volume control, syncopation, intonation, versatile flow, pitch control, etc. of any rapper. If this were ranking their solo careers, I would put Royce at 1. However, when he raps in Slaughterhouse, he lacks that energy and versatility. And when all 3 other members step up their game, I think he's last.
#3 Joe Budden
I'm upset to put Budden at 3, especially because he is not far behind the other two at all. In fact, he is very close. I love Buddens calm-laid back flow. He is a great lyricist. He doesn't need a big vocabulary or a bunch of wordplay. He proves that all you need is a good message and a good flow, doesn't matter how simple it is. I just think he lacks the versatility that Ortiz and Royce have.
#2 Joell Ortiz
People usually put Ortiz last, and in terms of the lyrics that he WRITES they are probably right, though he does have a great sense of humor. However, when it comes to delivery Ortiz has some of the best in the game. The instrumentals Ortiz has used in his solo career were a lot less intense than the ones he's rapping over in Slaughterhouse, which made him step up his game and rhyme faster. His voice is versatile and can change in tone and accent whenever needed.
#1 Crooked I
Crooked I has made the biggest improvement since his switch from solo career to Slaughterhouse. He is a very consistent rapper. None of his verses on the groups songs are duds, and in fact, in a majority of the Slaughterhouse songs, he dominates the rest of them (even including some of the songs with Eminem on it). Like Eminem, Crooked I uses as many multisyllabic rhymes as possible, trying to make almost every word of the song rhyme.