Hi Rich.
I have used Conti TKC's and Pirelli MT21's.

When I got my XTZ last April I fitted a set of TKC's...a great all round tyre and fine off road on anything but wet grass and mud.

When we had the Plain ride-out I had then fitted a MT21 on the front but had left the TKC on the rear as I thought it would last longer,but by 2,500 miles the rear was over half worn, so I fitted the MT21 I had,and that is how it is today.Mind you....if I did not allready have the MT21 then I think I would have run with the TKC for another thousand miles and then fitted another.

So my choice-
Pirelli MT21 on the front (for more off road grip when wet and will last for ages).
Conti TKC on the rear (wet off road grip not so much an issue on the rear and more miles on the road).

BTW...on my XTR,all I ever used were the Pirelli's.

Cheers,
Andy.