What artist has been consistnently killing it on guest appearances?

In light of the K Dot and Jay-Z thread, I 'm curious who you think has been laying down the best guest features over the years. I think an obvious candidate is Busta Rhymes. Seems like the dude has made a career off of giving guest verses - and that makes sense when you consider his talents as a rapper. He has tremendous mic presence (Flava In Ya Ear and Simon Says Remix), one of the best lyrical deliveries out there (check out his monstrous flow on Outro and Look At Me Now), and has proven himself to be a versatile rapper when it comes to subject matter and content (check out Black President remix and Doctor's Advocate). I think he's clearly one of most consistent guest artists in da game. When you're able to stand your own against the likes of Biggie, Redman, Nas, Lil Wayne, Mos Def, and so many others, then you've earned your points!

Here a few of his most notable guest appearances -

Look At Me Now - Chris Brown ft. Lil Wayne & Busta Rhymes (2011)


Lil Wayne - Outro ft. Bun B, Nas, Shyne & Busta Rhymes (2010)


Black President (remix) - DJ Green Latern ft. David Banner, Busta Rhymes, Talib Kweli (2008)


Can't Tell Me Nothing (remix) Kanye West ft. Lil Wayne, Young Jeezy, Busta Rhymes


Doctor's Advocate - The Game ft. Busta Rhymes (2006)


Simon Says (remix) - Pharoahe Monch ft. Lady Luck, Redman, Method Man, Busta Rhymes , Shaabam Shadeeq (1999)


The Assignment - Nore ft. Busta Rhyme and Spliff Star (1998)


Do It Now - Mos Def ft. Busta Rhyme (1998)


Yeah - Keith Murray Ft Busta Rhymes, Redman & Jamal (1996)


Flava In Ya Ear - Craig Mack ft. The Notorious B.I.G., Rampage, LL Cool J, Puff Daddy (1994)


Scenario - A Tribe Called Quest ft. Busta Rhymes, Charlie Brown and Dinco D of Leaders of the New School (1991)