I really love a very subtle (just about audible) flanging effect added to a nice mellow overdriven tone - even more so for a Marshall style driven tone.
I read there is flanger on Free - All Right Now, though I don't hear it myself. In any case the combination works really well.
A different example where you can tell there is definitely some subtle flanger in play is Rory Gallagher - Follow Me.
I haven't tried enough pedals to even put 5 together though...same with the other categories, will leave that to those with more experience.