tldr; Stick to the latest even number Node versions for the longest period of support. Use the highest numbered versions for the latest and greatest.
In the end, I feel this is pretty nice, with a new LTR each year at every other version. The down side imho, is I really hope all the stage3-4 bits of ES make it into V8 before Node version 8 is cut in 6 months, I know a lot of those pieces are slated to make it in. I have the feeling that with the extra bits that are pretty far along in ES stages, that there won't be need for too many changes to the core engine for some time, at least in terms of ABI/API.