So as someone pointed out earlier you can go leashless on any pair of tools. I'm guessing when you say leashless you mean a double handle design (right?)...
If you are planning on any alpine in the future and since you are only getting one set I would recommend something that doesn't have the double handle design but does have at least a fang... if it has an upper position (BD calls it the strike) even better.
Tools would work for this include:
BD Cobra, Viper
Petzl Quark, Aztar
Grivel Alp Wing, Light Wing
I'm likely forgetting a few but you get the idea.
If you want the double handle design and dont want to pound pins I think the nomic swings best of all the double handle tools on the market.
The BD reactor swings "more naturally" that the BD fusion but if you spend a lot of time on your tools you will learn to swing whatever you purchase.
The quark ergo swings better than the fusion but not as good as the reactor IMO. Again... time on your tools will fix that.
And FYI the new cobra is much much lighter than the old cobra. It is actually almost identical weight to the quark. And speaking of weights the flat grivel tools (monster, x monster, etc) are some of the heaviest tools on the market. I would say make yourself a list of tools/weights and compare them.
I will likely be in Bozeman this month before the fest so if you want to demo
nomics
quarks
fusions
reactors
cobras
and maybe vipers
get a hold of me (PM me your info).