Any ab exercise is good but id recommend do full body bodyweight program because every bodyweight exercise uses your one way or another.

Example of full body weight programs?

Look up 350 bodyweight I do a modified version of that I can give my workout but it takes 1 hour 50 mins

A basic example n is say 3sets of 15 squats 3 sets of 10 woodchops each side with med ball max pull up one rep 3 sets of 10 push ups and do 3sets if 10 jackknife or v sit ups that's just a basic program but Google bodyweight program and you can get a variety of different program and exercises that suit you but th

I will try.thanks