[naptown CR]

You are building cabinets and are desiting to put a gloss finish on them and use AC plywood? Are these going to be outside? If not spend the few extra bucks and buy birch or maple plywood and stop beating yourself up on the prep. No amount of sanding will make that very smooth and once a latex coating is applied the grain will swell and look bad anyway

 

[naptown CR]

If this were an exterior application I would use a latex however these sound like book cases which would be inside. I would use an alkyd primer so the grain doesn't swell too much and sand again after. Just be aware that the gran and boat patches will show through and a gloss finish is not at all forgiving