At a low enough level that a character only has one BAB, is there any incentive to using a full attack, or is it more advantageous to hang on to the move action and use a standard attack?
It matters for some characters
If you have, for example, Two-Weapon Fighting, Flurry of Blows, Rapid Shot, or haste, you may have more than one attack even though you have low BAB. You would need a Full-Attack to use those. Even with only one attack, some characters (e.g. a 3rd-level Swordlord Fighter) can get other benefits from making a Full Attack, and therefore may Full-Attack for just one attack, burning their Move action for the sake of that bonus.
But if you have only one attack and don't have any other special feature that references Full Attacks, there is no reason to choose to use one; you'd be burning your Move action for no reason.
Note that you do not choose between Attack and Full-Attack until after that first attack (assuming you still have a Move action to make the Full-Attack an option).
The first attack does not require a Full Round action
Please see the following from PFSRD:
If you get more than one attack per round because your base attack bonus is high enough (see Base Attack Bonus in Classes), because you fight with two weapons or a double weapon, or for some special reason, you must use a full-round action to get your additional attacks.
After your first attack, you can decide to take a move action instead of making your remaining attacks
Thus, your first attack is always considered a standard action, no matter what your maximum number of attacks are from all sources. There is a note saying that as long as you have at least a standard action you may consume it with a full round one but that's for non attack related options. So given the rules above, you're not cornered into a full attack at low levels.
Edit: A Charge attack is a Full-Round action but without examining each special ability (maybe you have a character in mind?) there is nothing else.
Charging is a special full-round action that allows you to move up to twice your speed and attack during the action. Charging, however, carries tight restrictions on how you can move.
If you only have one attack (which is not the same thing as having only one BAB), then as far as I'm aware, there is no need to use the Full Attack action at all, because you would get the same number of attacks either way.
I suppose you could declare a full attack, even if that only meant attacking once. I can't think of any reason to do so; not within the basics of combat, anyway. But if some effect were to depend on using one specific type of attack (or action?) versus the other, then I'd let the player pick.