I'm not a huge fan, but does it seem to anyone else that these guys are a little underrated when it comes to greatest album lists?

No, because they were a singles band. I really like CCR but their albums were very hit and miss. If you are ranking greatest hits albums Chronicles would be near the top.

I don't agree with you
CCR is a great band and the albums are good
I listened yesterday to Cosmo's Factory and side 1 is a killer
I rank that album in my top 20.

The two Creedence albums I have (Cosmo and Green River) are top notch. Just listening to them makes me wish I was there.