Weak Notrump vs Strong Notrump

Below are some arguments that might be made ('weak' is 12-14 and 'strong' is 15-17):

Weak NT

1. When the weak NT is not used, there is an inference that opener is either stronger or more distributional that a minimum balanced hand, so for example, major suit raises by opener don't cover such a wide range.

2. The strong NT leads to more awkward situations where it is necessary to open 1NT offshape, because the hand is too good to rebid 1NT or repeat the suit opened, but is not strong enough to reverse. The weak NT also has some offshape 1NT rebids but they are less frequent.

3. Any 1NT bid leaves your side well placed in competitive auctions because it is limited in both strength and shape, compared to opening 1 of a suit. This favours the weak NT because it occurs more often.

4. Typical methods over 1NT are not well suited to constructive auctions so a weak NT will cause opponents to miss games and/or overbid. Alternatively, they can play overcalls as always sound but risk losing the partscore battle.

Strong NT

1. The weak NT is more likely to go for a large penalty.

2. Playing weak NT, the strong NT hands can be awkward when interference prevents a 1NT rebid. The hand is better than minimum but further action may still be too much.

3. You may lose your own 4-4 major fit after opening 1NT. This is less frequent with a strong NT and also less dangerous because 1NT will often make anyway.

I also think investigating slam or the best game in an uncontested auction is more difficult after 1NT than after 1 of a suit. Traditional methods over 1NT make poor use of the available bidding space. It's not clear which side this favours as the weak NT is more common but the strong NT makes it more likely your side has a game.

I'm not attaching weights to these factors at this stage - just trying to identify the issues.