best app for excel and word on mac

Have had a couple of instances where the excel spreadsheet or word doc was so garbled when I opened it with either pages or numbers it could not be used. What is the best app for opening these files? I rarely use them for work. It's mainly attachments that are sent to me such as order forms, etc that get messed up in the conversion and then I can't use them. Thanks in advance for the help and suggestions!