I've been listening to a lot of the Human Equation album (at least, the parts that I could download), and I must say they are the most impressing. It seems like a concept album from what I've heard, and I always like good concept albums.
I would definitely consider buying the album, from what I've listened to. So far it's great, and I like how it has several re-emerging themes.
I also downloaded a couple of Genesis albums from Limewire, which were luckily avaialalble in full album format (it's much easier to listen to than setting up LPs). I listened to all of Nursery Cryme and some of Selling England by the Pound, and, though they were quite good, they confirmed my opinion that Lamb Lies Down is still superior.
Furthermore, because you liked Human Equation, I'm almost positive you'll like Lamb. It has a similar concept, several re-emerging themes, a similar sound in some aspects, and it's a double album. The first CD is actually quite a bit better (it has better songs and less filler) but the second CD is still quite good. I reccomend that, if you do buy it, that you get a more recent remastering, because that always helps the sound.