To me, a signature print is like this: You wear it before it becomes trendy, you rejoice when it becomes trendy because now it is easier to find everywhere, and you will still be wearing it when it is no longer trendy, because you love it and it feels like "you". If you see an item in that print, you immediately want to at least try it on, no matter that you already own several. Other people recommend or give you items in that print, because it makes them think of you.
For me, the signature prints are Breton stripes and any kind of plaid, tartan, or houndstooth. I will probably get bored with leopard and zebra eventually, and maybe with polkadots, but I will still be drawn to every striped T I ever see.
My suggestion: get some items in the buffalo plaid. But limit it to 3 or 4 for now. If you feel great in it now, and 2 years from now you still love it, reach for it, and crave even more of it, you will know you have found your signature.
(A caveat: every fall, tartan is very briefly the new IN thing, and I think everyone craves it because of back-to-school associations. If this is one of your signature prints, you will still want to wear it lots in January.)