Leaders to main line...again

[Ghoti]

Seems I've lost the leader on my last retrieve (goodness knows what I was snagged on ).

When I got the rod and reel I was told not to use a double uni knot to join the leader (8lb mono) to the main line (6lb Fireline) as it has too high a profile and bangs through the guides.

Yes I was told what kind of knot to use, and shown how, and thought I'd remember. But that was three weeks ago....

What knots would you use (other than the double uni), particularly with strength and "smoothness" in mind?

Cheers,
Scott