There is no best way, there is whatever way ias best for you though. Your options are to:
1) buy the software outright such that you own a license for it that does not expire. Purchasing gives you two options...
a) download the software
b) buy the discs
2) join the cloud and rent the software on a monthly basis
In any case, the best thing to do before you buy anything is to install the trial version and make sure what you might want to buy is capable of running on the machine you plan ot use it on.