If you're not Emperor before most of France is gone you're not rushing the diplo route.
The Africa > Ottoman > India > Emperor route (or Byz > OE > India route) is slower than Emperor+Vassal Swarm > Ottomans > Russia
But if you don't want to tag switch from Spain to the HRE it's a bit of a waste if you want to one tag, still I don't disagree, I just don't like going 90% of the way on the HRE, which I've only formed once because I just want to stay Spain, and last time I did the flipping around it broke all the treaty of Tors whatever it is.
Also, don't forget the Commonwealth, it's available to all Christian nations, you can fairly easily get a PU over them around 1600-1610 if you are lucky or you may have to fight them for it, but dang, in my latest game they diploannex Savoy and a few other places before my 63 year old King flipped their country to a Kingdom in 1604, giving me only a time crunching and scary claim throne war. We were the only two great powers in the Euro by that time, but I had pre planned this by allying with a Novgorod Russia, so it was go time and a lot of fun.
Try it at home, heck I just supported my heir since pretty much 1450ish, had two kings including the last one, you get a huge +200 relations boost from getting your dynasty elected, but you got to park a dip there for a hundred years. You can help yourself by spreading your dynasty to other claimants, so even if it is not your candidate it could still be your dynasty. I think I had one Bohemian King in the early 1500s with my dynasty on the throne but I wasn't paying very close attention.