I use foundation paper because I bought a couple of packages years ago and am still working my way thru them. I like that they are the same size as copy paper and my printer has no issue with them. I also like that I can easily see thru them and that they are easy to remove.
But one of the parchment paper brands is now advertising pre-cut cookie sheet pieces--17"x11". Cutting one of those in half would give me the same size as copy paper too. I haven't seen it in any local stores so cannot comment on the price.