I'm pretty sure you end up in the same place no matter what you choose, but is there a listing of the dialogue choices to make and when?
Aside for which Summon Beast you get at the beginning... Well there aren't, since the dialog choices will put you on the same path for the story unless it's a "No I'm not ready" or "I'm ready" question. At best: other questions offer different dialog between characters. And since holding R+B skips text almost instantly, and unless you REALLY want to count the textboxes in each choice for the fastest option... Most of the time the difference between A and B are incredibly minor. The only real time where the textboxes matter greatly are noted in the guide. IE when given the option to sell your swords at the beginning of the game to the Gold Guild, or later in the game where you need to tell someone some grievous news.
For any other question (that progresses the story no matter what you answer) you can choose A or B. Picking A just saves an input. Doing research on each dialog and how many textboxes you'd get would only really be valid for frame wars, imo, since the game is already long enough.
About the Summon Beast chart, here's one: https://gamefaqs.gamespot.com/gba/583203-summon-night-swordcraft-story/map/5064?raw=1
