Double Uni. However for casting its a bit bulky so other knots are slimmer.

For BB, Jig and plastics from a boat casting not so critical and I just use a double uni.

Try an albright with the lighter line doubled if you're getting problems due to the large leader size. You can also try a reverse albright (link). I just dont like double unis when the line diameters are quite different. Gives 50% of the line strength or worse under some circumstances.

For joining a leader to light mono for trolling i've occasionally used a GT knot (which surprisingly works if theres enough difference between line sizes). Also, this knot is good if you have a double in your mono: http://www.fishnet.com.au/library/knotsrigs/tedsleaderconnection.html
Also consider the slim beauty.

Depends what you're fishing for. If i'm using 6-8kg mono, its usually aiming for fish heavier than the line weight so I like every percentage of the line strength I can possibly get out of it (Aussie plait/bimini  to a few diff knots can give practically 100% line strength). Bit diff if baitfishing on the beach say though where you may want a good, but not necessarily perfect knot (that may be quite time consuming).

Are you shore based or boat? Will you be casting the knot through the guides?

Personally I wouldnt use a uni/uni for 60lb leader if you are distance casting and it is running through the guides. I use a uni/uni for anything up to 20lb leader. For 40lb to 60lb I use a PR or FG knot if running through guides or a bimini (or spider hitch) to GT knot if using short leader where the knot doesnt travel through guides.

Despite what I have said above, I often end up jsut doing a  uni/uni if I have to retie anything at the beach in the wind.

 I personally use an Albright, for ease, when im fishing.  If i am rigging up the night before, or when time isnt of the essence, I use a bimini to GT knot. 

Cheers guys for the quick responces ...

As hlokk mentioned, I'm looking at long (3-4m) leader, casting from boat for say mahi mahi, and using line class lighter than fish weight (game fishing points ) and my whole aim is to increase the percentage of strength .... I've been also told that double uni isn't the best for great strength difference between line and leader.

It flies through guides.

PS and oops I didnt even look at 3kg to 30-60kg. I wouldnt go the Uni at all with that veriation. I read mono to flouro.

Hey Cransy,

Does the slim beauty work on mono to mono (or FC)?

I have tried it a few times but it always slips. But seems fine with braid to mono.

Obviously it doesnt slip for you??, so i must be doing something wrong???

Cheers

P.S. : ive only ever tried it between 30lb mainline and 80lb leader. Never with a lightish mainline.

I have just tied all my trolling stuff 5kg and 10 kg mono to 60 lb leader using bimini to GT knot. Tried a few other options, this seemed best for mono to mono.

Hate double uni, bulky and just looks wrong, but some swear by it.

 Just did all mine too, but using Slim Beauty on all my light game ones, 2-4Kg to 60lb leaders, thanks guys for your thoughts, almost forgot about it! Also used Allbright to all the rest.

Agree with JohnF and Hlokk, Double Uni is great, but best in joining lines of similar diam etc.

Cheers all