Which reel rod combo would be best? The 7 and MH or 6.4:1 MH or vis versa?  

what are your intended presentations with each rod?

M set up will be senkos that sort of thing, MH spinnerd ect

M 7.1, MH 6.4, that's how I would personally do it. Though you should try it both ways and see what you like ir best.

IMO, its personal preference and depends a lot on what you're going to fish on each rod. I use 6:1 for everything.

You're looking at it backwards, start with the intended purpose and then go from there. For example, if you want an all purpose rod then I would look at a 7' MH fast action rod with a reel that has the 6.4:1 gear ratio, if you intend to use frogs or cranks then you would look at something different and you can't just limit yourself with 2 options.