Raw, Yossha. The point of Lightroom is that it's primarily an excellent Raw converter, so you'll waste much of its ability and value if you only throw jpegs at it.
I agree that Lightroom shines as a RAW processor and editor ...
But also Lightroom does a great job cataloging and editing your previously captured JPGs
Oh yeah, true enough, but I didn't get the sense that the original question was about Lr's DAM capabilitles - and Lr wouldn't be my first choice for a jpeg editor.