He churns out music at an incredible rate and goes all over the place in the process. One can only wonder if there's a record he DOESN'T own, because the volume of music he's produced would amount to about 5 producers' worth.

The reason I compare him to Frank Zappa is because of Zappa's notion that even his most die hard fans won't like all of his music because of how different it all is, and the same goes for Madlib. You can call it hit-and-miss and not be wrong, but I don't like to call it that because it all touches on such different angles of music that a miss doesn't always mean it shouldn't have been made.

Anyway, Madlib is a hip hop and jazz artist and his strength is in hip hop. His jazz is really cool and enjoyable, though I wouldn't classify him as a true jazz artist. He dabbles, and it usually produces interesting results, but it probably wouldn't impress a true jazz head in any fundamental way--though I don't know this for sure given that I am not a jazz head nor know any that listen to Madlib.

Jazz projects of his aside, his hip hop is very progressive. I'm surprised more people don't use the term prog hip-hop because that's exactly what Madlib and Dilla were. They both pushed Hip Hop to these weird new levels that still stay in the realm of hip hop (unlike FlyLo who I think officially crosses over into "electronic"). Madlib is absolutely one of the true progressive producers there ever was and this sort of spawned with the creation of Quasimoto. As a hobbyist producer myself, Madlib is an inspiration and probably appeals to people like me more than anybody else. I'm trying to say that without sounding elitist and I don't mean to suggest that my ears are better than others, but he is definitely a producer's producer first.

Ahem, moving on to your original request, my suggested required listens of Madlib's music starts with the following:

Lootpack - Soundpieces Da Antidote LP
- Despite his production for Tha Alkaholiks many years prior, this LP is sort of where Madlib was born. Jay Dee notoriously cited this LP as inspiration for staying up late to make beats again as a sort of newfound competition in Madlib.

Check out: Hityawitdat, Weededed

Quasimoto - The Unseen
- If you can get the over voice like I and all of the other Lord Quas fans have, this album is brilliant. The beats are jazzy, spaced-out and very much "left-field" but man are they dope.

Check out: Low Class Conspiracy, Green Power, Axe Puzzles

Madlib - Shades of Blue
- So Blue Note let Madlib make an album of him reworking his selection of Blue Note recordings and it is fantastic. As someone once said "A Jazz album for fans of Hip Hop and a Hip Hop album for fans of Jazz"

Check out: Stepping Into Tomorrow, Please Set Me At Ease

Madvillain - Madvillainy
- MF DOOM + Madlib is an unsurprisingly perfect combination and remains both of their stamp on hip hop.

Check out: All Caps, Accordian, Fancy Clown

Quasimoto - Further Adventures of Lord Quas:
- This one's even weirder than The Unseen and is a little more exhausting in some parts, but the beats man, the beats...

Check out: The Exclusive, Crime

Madlib - Beat Kondukta - Vol 5-6 The Dil Cosby Suite
- This is what Madlib sounds like when he's focused, and many consider it his best work because of it.

Then he went and made all of those Medicine Show releases which are even MORE exhausting to make through because he littered them with so many skits. But, like Madlib, it's worth going through because you'll probably end up finding one of your favorite beats along the way.

The albums I listed are his big ones that most people like. I personally think the following are either as great or underrated:

Madlib - Beat Kondukta - Vol 3-4 Beat Kondukta in India
- Maybe I just like the "Bollywood" sound but this album is serious heat and nobody seems to ever mention it when talking about Madlib. It's a personal favorite. Same goes for the Africa one.

Jaylib - Champion Sound
- Madlib really brought the heat on this album and outdoes Dilla on the beats which should say a lot about the quality of his production on this album. His rapping leaves much to be desired. A very enjoyable album.

I'm rambling at this point, so I'll let that be the evaluation as to whether or not Madlib is an artist for you. This is only the tip of the iceberg for someone like him, and you'll find beats of his on various albums from Ghostface to Erykah Badu. You'll probably spend years trying to hear everything if you really wanted to.