Yeah I think the question is how does one define "best teamplay clan". If we're talking the most disciplined, then probably Hoplites or NH. If we're talking the most effective I'd say KUTT, but as mentioned that's mostly a product of lots armor, strength, and long pointy things.
But lets be honest - as cool as it looks sometimes to see shieldwalls and formations, they rarely are effective. I think working with 1 or 2 other people is probably the max you want to have, provided you're sticking with your team. All you need is one other person who you are in-tune with to single-out enemies, and that will provide you the most mobility in battle while reducing the amount of teamhit clutter.