I use both Sharkskin and Lavacore.
I have found both to be very good, though of different reasons.
In winter I dive with Lavacore as my preferred lining, as it seems thicker.
I like the Sharkskin, but more for the fluffy lining, which doesnt have the harsh seems that the lavacore has, so I suppose it is more a matter of taste than design.
I cant think of anything more relaxing, than being in the downunder, breathing some nice clean fresh filtered 21% nitrox.