Leader material help.

Hi all,

I have just bought some Orvis Super Strong tippet material for making
leaders, x3 x5 and x8.

I am using the standard recommended blood knot to join the lines together,
the trouble is the x5 and x8 snaps at the knot point, given the slightest
hand pressure.

I am taking this Orvis crap back to the shop ASAP, hoping for a refund

Prior to this I had been using bog standard mono as used by coarse fishers
but thought I would be clever and buy the fly stuff as it looked much
thinner.

Who makes the best tippet material these days ?.

Thanks,

S.