If you need Microsoft format documents for work, then buy Office; there's no other way to ensure trouble-free compatibility. If you can work with Open Document formats, then I recommend LibreOffice or OpenOffice. For sporadic home use, Kingsoft is good enough, although I really don't like how it always schedules a task to look for updates every one hour, no matter how many times you diasble or delete it, or whether you disabled automatic update checking via the program's options. SoftMaker Free Office is similar to Kingsoft, minus the modern UI and the enforced update checking.