Nelson Pass's favorite is the Aleph 2
Monoblocks, 100w ea. I believe
The Aleph 4 is 2 of these in one box but with less bias current.
Not quite as good apparently-of course very very good nonetheless
Go to: passdiy.com to find out more
Also you really should spend an hour or two just doing searches on this site regarding Alephs-it will clarify, also you will discover things like circuitboards available, etc. You will need all this periferal info when you actually built it -trust me!!
Also you won't be asking the same questions already asked
This question for example has been addressd before.
If you feel you are very capable at the art of DIY'ing then you might try the Aleph 0's or 1 or 1.2, but you'll be a relative pioneer in this area. If you think you might need some assistance from this forum and ready made board designs and others with their experiences building Aleph's, you should stick with the Aleph 2 or 4. There are many who have finish or are currently working on these Aleph clones frequenting the forum now.
P.S. As I was writing this post, I knew I seen something on the Aleph 1.2 recently. Well here's the link for 1.2 boards.