People don't like ranking the DO schools. I think with MD schools it is slightly more useful as there are so many of them that you need some help making general categorizations but with DO there are few enough that you should be able to formulate your own preferences. They are all 'good', but they are pretty different. The question you have to ask yourself is what do you want in a medical school. Then look at the schools to see if they are 'that type of school'.
eg for me, one consideration is location - I want to live near or in a big city. That immediately rules out some DO schools. The middle of Appalachia would not suit me, regardless of how good a school it is. Whereas PCOM, CCOM, TUCOM, NSUCOM all win on this front. NYCOM also wins on this front but loses out on others...
Then there is the atmosphere. I have heard some schools require you to be in 'professional attire' meaning a shirt and tie at classes. I think this was LECOM (?don't sue me if I'm wrong about that - LECOM fell off my list for other reasons which were more important so I didn't pay much attention to it after that). Again this doesn't appeal to me. Give me the relaxed atmosphere of say TUCOM anyday.
Then there is emphasis. Although all DO schools have a primary care emphasis, some schools eg NYCOM fell off my list as (in addition to very heavily favoring state residents which I am not) they are very structured towards primary care (more so than say PCOM, which is on my list).
Then there are other more intangibles such as the feel you get for a place. I am not applying till next year but as my job makes me travel to the same areas DO schools are in fairly often I have visited several of them already. CCOM wins high marks for me just in follow up - I requested school catalogs from PCOM, NSUCOM, TUCOM and CCOM. ONLY CCOM sent one!! I requested school catalogs again, emailing the admissions deans directly. I got a reply from TUCOM saying it was going in the mail. It has never come. Neither NSUCOM nor PCOM even replied. I tried again with them - still nothing. In the meantime CCOM has not only sent me their catalog and additional brochures but just yesterday sent me a follow up letter telling me about an open day at their campus for prospective applicants. I can't go as it clashes with an out of town trip which is highly unfortunate BUT such things make a big difference to me that their admin keeps records, makes the effort, follows through. That's not something I could have learnt from looking at USNEWS rankings, etc.
Then you can look at hospital affiliations and what you want from your time. eg I think PCOM and NSUCOM require some time (3 months?) in a rural area as part of your rotations. This is probably great for clinical exposure but is it something you would want? CCOM and TUCOM both have great hospital affiliations BUT with CCOM you can do all of these in the Chicago area ie no moving involved. With TUCOM where your rotations are are decided by lottery and are all over the country (New York, Las Vegas, the Bay Area). You might like the idea of moving around and seeing/living in different places. You might think it sounds exciting. On the other hand you might have a 4 year old and thus think this sounds like a major pain in the ass.
If you want to do research look at the schools that offer PhD-MD even if you don't want a PhD, the fact that a school offers one indicates they are more research oriented. Frankly (and I know this will upset some folks but I think it so I'm going to say it anyway...) if you are really interested in research, unless it's specifically research into OMM, I think you would be better off going to virtually any MD school. Have you SEEN the research facilities at even the best DO research schools?? Not good. Neither is their level of research funding. Having said that, thats not really ever been an emphasis in DO schools till recently.
So...make a list of the things that are important to you...and then check to see how the schools match up..
