It depends on your situation. If money is no object, dropping 6k credits on a Tour Plus set will launch you into very low scores very quickly for as long as you are in lower tiers. But, 6k credits is a hell of a lot for clubs you won't use once you make the Master tier.
If you are on a budget and just want to hold yourself over, spend 99 credits on the Starter Plus set and just ride them till the wheels fall off. The levels are seriously going to fly by, especially if you can get your 880xp bonus every day. I would use that driver until I got to the lvl 29ish R11 and then ride that to Master where you'll likely need to upgrade again.