What?
Anyways, they made a GH compilation for Genesis back in '99, but it's 95% Collins-post-Hackett-era. Nothing from the Collins-with-Hackett CDs (Trick of the Tail and Wind and the Wuthering, both worthwhile pursuits) and only one-and-a-half Gabriel songs in "Watcher of the Skies" and a remade "Carpet Crawlers" with dual vox from Gabriel and Collins.
The two live CDs RB mentioned are good starting points. I haven't heard the first two albums (FGTR and Trespass, which had Anthony Phillips instead of Steve Hackett), so I'd rank the Gabriel-Hackett albums as such
1. Selling England by the Pound
2. The Lamb Lies Down on Broadway
3. Foxtrot
4. Nursery Cryme