I like those last 3 the best; each is good for a different reason:
6:5 is possibly the best raised-caps ratio, in my opinion — though something a bit smaller (like the less-rational 15:13) might look even better to me.
At 9:8, this is a very subtle raised-caps ratio, which some who aren't fans of the raised-caps might find more palatable. The first letter is the same height as lowercase letters in the legend, and the rest is the same size as typical action messages that don't get raised-caps treatment. This is a close match to what I'm used to seeing in button copy around central Ohio, while incorporating subtle modern design changes (most notably Series E instead of E(M) or D(M), and of course the larger initial letter).
This ratio of 5:4 seems more common. There's still the advantage of size similarity to action messages. While the first letter is now larger than lowercase letters in the destination, it's not by a noticeable amount. If the destination is in Clearview, the size might match well. I think ODOT's newer installations (Clearview and FHWA) might be using this set of sizes, at least on
the freeway. Signage for entrance ramps sometimes feature exaggerated raised-caps directions and undersized destinations. (Possibly 15"/10" direction, 30" shield, 12"/9" destination, though my memory could be parodying reality here…)