I've done a lot (most) with various word processors, but also Campaign Cartographer, tried Excel once, and once a long time ago made one with MS Publisher I believe it was. Really, of the formal character sheets I've made over the years, almost as many were done using a TYPEWRITER, ruler, and pen then just made a whole bunch of copies at a local print shop, as I have with word processor (Word or Open Office) to print up at home.
What you use depends on several things - the game you're making a sheet for, the look you want to try to end up with, familiarity with the software you're using or happen to have available (or hardware as the case may be), and the amount of effort you put into it. If you have the skills you could hand carve a negative in wood and use it as a stamp to print copies. You could write it out by hand on stencil and use a good old-fashioned mimeograph if that's the look you want. The most recent ones I've made I use Campaign Cartographer because I understood how to use that to put in borders and graphics easier than with Word. In a file folder though I still have some blank D&D sheets one of my DM's did up with a typewriter, ruler and pen back in... 1979 probably. He had them printed on green paper and glued up into a tear-off pad at a copy shop. You could use Paint, or Paintshop Pro, or graphical pencils and a drafting board.
Yeah, there's more options out there than you can shake a stick at.