Haven't been on 14, but 14A from Cody to Sheridan is a great ride. If you fish, the North Tongue River, right in the middle of the route is some of the best fly fishing I have ever done.
It's pretty close to a coin flip. There are some pretty steep inclines after Lovell and some great lookout points. The Greybull route has more rock/rugged mtn/canyon scenery and you can stop and check out Shell Falls. Seriously you can't go wrong either way.
I have been over the Big Horns a few times. I go in one way and out the other. The last time I went out through the Shell Canyon, I think it may be the best.
Little higher elevation if you go through the Lovell, but I think both routes are fine. Shell Canyon is nice to see, but the Wyoming High Country is to. Stop in Bearlodge either way and have a beer or the other 2 places are nice also.