If you have a choice between playing in notrump vs playing in a minor suit almost always choose notrump. This is especially true if choosing between 3NT and 5 of a minor.
Almost always choose 3NT. The main reason for this is that it is invariably easier to take 9 tricks at 3NT than it is to take 11 tricks at 5 of a minor. Another reason is that at duplicate notrump scores higher than a minor suit if you make overtricks

For example, you have K3 9 7 3 A K Q 4 3 Q 5 4 and partner opens 1NT.
You have enough points for game and you have a very nice diamond suit. Resist the temptation to bid diamonds. Bid 3NT. If the hand is at follows: