Which Microsoft Office 365 Plan is more cost effective or worth it?

I'm curious to know, which Microsoft Office 365 plan is more worth it, cos the standard personal 1yr subscription is $108/Yr when the home and student 1 time purchase is double that but no need to renew unless important update required. For someone who is requires MS 365 on both phone & computer, is better to get the subscription one or the 1 time buy then wait for est l. 5yr then consider buy the latest 1 time buy version? Any thoughts on that? I'm currently a NSF, so money is a concern for me.