good question, a dramatic change or small change.
I can't actually give an answer, but the smaller changes are working well for me, and I keep adding changes.
I started with just accepting being obese, being fat. Calling myself fatmad here is an acknowledgement of that. I wasn't sure I was ready to "diet" or do what it took to lose weight tho. I did decide to change some destructive behaviours, so came to this forum to try to get a grip on bingeing.
As that got better, I started to work on avoiding late evening snacks, and then smaller portions of food. I started to add more exercise, just a bit at a time. (I started with what I thought was most destructive to me)
I have done each thing about 1-2 weeks apart. Just working toward a healthier lifestyle.
I have lost weight gradually, without ever really dieting.
I am starting to up it now, trying to make regular exercise a real part of my life. One of the things I have been happy with (including the gradual weight loss) is that I do feel I can maintain this in the long term. I figure there is no point in losing weight if I can't maintain it and keep it off.
SO I do highly recommend small changes. Keep them going, and keep them up. Make real changes you can live with.
good luck, hope you find your path