1) Better quality of life. DOs practice longer, are happier and have lower suicide rates. I have met a lot of successful MDs who are not happy about their lives; this has never been my experience with DOs.
I have also found the DO community to be more friendly collaborative and relaxed than the MD one.
2) I think OMM is very valuable. It helped me a lot, I have seen it make big improvements for patients who otherwise could not be helped, and it is something I would enjoy practicing.
3) Being able to accurately diagnose patients and ideally treat them without referrals is very important to me. I feel DO schools, at least the one I am going to do a very good job at this. I have seen extremely inconsistent results in this regard (at least by my standards) from the people I know who went through MD program.
I don't feel a 200k salary vs a 400k salary really matters compared to quality enjoyment and satisfaction of life. For the highest paying residencies, it is true that you have better odds with MD, but I think that link is actually a bit spurious. The main thing most residencies care about are board scores, and only super smart people get high board scores. The super smart people are normally in MD schools, and thus MD 4th years have better test scores than DO 4th years, which allows them to get the coveted residency spots.
Every residency I potentially want to go to is accessible to me with the path I'm taking, so I feel all around pretty good about my choice. Ultimately my main advice for anyone pondering this question is to think the whole process and path through, from the start to the very end, rather than just stopping at say "which will get me into best residency."