Ours is mishmash - lots of different bits bought over the years - but it all seems to hang together quite well.
Lots of wooden decs in red and green
A load of salt-dough decs which are just about ready to drop to bits! I made them when the dds were babies and we probably "lose" one each year!
Some which I bought in the States when I worked there
Some which dh and I bought on our honeymoon
Some decs that were given to my parents when I was born/little
Some decs bought for the dds or made by them
Each year Santa brings them a new decoration for the tree.
Tree is full now! But it is lovely getting out our old "friends" and remembering how we came by them.
I do like the look of "matching" decs on trees but I like my memories!