what would be the best overall gear ratio for a crankbait specific rod?

What depth crankbaits? I uses a 5:x;1 for most. If I was going reel deep might go down to a 4:1. I like the 5:1. Because I tend to fish fast so this keeps my baits a bit slower. I also don't really fish deep cranks.

I've found that 5.3:1 or 5.4:1 works the best for crankbaits.

 

A slower retrieve allows you to "work" the crankbait more.

5.4:1 is a good all around ratio, but also depends, sometimes he 6:1 ratio's work well also depending on the crankbait and time of year.  Slower works better on deeper baits and keeps you from wearing yourself out, the other I use on squarebill and shallower running baits when I want to get a faster reaction strike.

Mid to deep runners I use a 5.x:1 ratio. Squarebills, lipless, and any other shallow cranks I use a 6.3:1. I throw a lot of squarebills and burn them really fast with a 6.3:1.