I'd say none of the above. However, there are people claim to have success with all of those diets - different people respond to different foods.
One of my doctors recommended the FODMAP diet to me recently, but I didn't want to try it. I spent a lot of time in the past experimenting with various restrictive diets, and found them extremely unhelpful - some even made my symptoms worse. When I read about the FODMAP diet, it seemed to be very restrictive, and I didn't see any particular reason why it should apply to me. My diet's already restricted by not being able to eat foods which could block my stoma, so I didn't want to cut out any more, not without good reason that it would improve things for me.
The only way you'll find out if a diet can help you, is to try it and see, but I'd be wary of trying anything that has only anecdotal evidence. The diet that helps me the most is low-fibre. I believe this diet has more scientific backing behind it than the ones you mentioned. A low fibre diet is often recommended by conventional doctors, for various digestive medical conditions.
You need to consider your overall health at the moment before attempting any major dietary changes; for example, if you're very sick right now, or if you're underweight, restricting your food choices right now may not be a good idea.
Consider the time and financial cost you have to spare - if you want to try a new diet, do you have the time to learn about it? If you knew a diet would bring a lot of health benefits, then it would be worth putting time and effort into it, but if you choose to follow a diet with no idea if it will help or not, you have to consider that you might not benefit, no matter how well you stick to it.
I think the most important thing is not to expect too much. Don't get stressed over following rigid rules, and don't believe everything you read - just because one website tells you certain foods are bad, it doesn't mean they are.
If you do change your diet, look for consistent improvement in your symptoms - just because you feel bad after eating a particular food one day, it doesn't mean that food caused you to feel worse - look for consistent patterns over a couple of weeks.
I'd recommend steering clear of any overly restrictive or "alternative" diets. You may want to get tested for lactose intolerance and coeliac disease. You could also start by eliminating the foods from your diet that are most commonly causes of digestive problems - high fibre foods, very rich foods, spicy foods, alcohol, etc. However, again, remember that virtually every food has been labeled "bad" by someone, so make sure you don't end up cutting out too many foods.
Don't get stressed about it or let it confuse you, and don't worry if you make some wrong food choices while you're experimenting. Eating something which disagrees with you may make you feel worse temporarily, but it shouldn't do you any lasting harm. There are some circumstances where this isn't the case - for example, if I eat a food which blocks my stoma, that can have major, immediate health consequences, and I think the same can apply to strictures and other Crohn's complications. If you have any worries about this, check whether your gasteroenterologist has any advice about foods you should be avoiding.