You see, I was trying to make a level that makes the ai OP at first, but at midgame, there are some areas where I could complete a bonus and some areas where I could prevent the AI from completing the bonus. I don't really have that many troops to do both of them at the same time. What should I do?

It really depends. Ask yourself the following:
1) How much income do I get from getting said bonus, and how many income can I deny the AI from getting by denying his bonus. Is it worth it? If the AI has 1000 income and I have 100 income, is denying it 10 income worth it, relatively, if I get 5 income for completing a bonus?
2) If I complete my bonus, does the AI border my bonus and can it break it the turn after I complete it, wasting my armies, basically?
3) I would make this a tricolon, but alas, no third point.

Have a good one

Edited 8/9/2020 12:02:10

What if they’re the same?

If they are the same, cutting through the enemy bonus is almost always the better choice in my opinion. For AI, it gives them less to work with, and I can almost always get that bonus right after. For humans, sometimes you can break their will and force a surrender sooner