I think they're about the same from what I've seen. The only real differences I've seen is that S30V has a little better wear resistance, but I like 14C's edge-holding capabilities when it comes to impact stress. I've had some gnarly deformations in S30V that took a long time to get out, whereas I dropped 14C on a honing stone and could not even see the deformation, and took it out in no time at all.
I haven't really owned my 14C knife that long and haven't had as many accidental impacts though, so who knows if it's really better at edge-holding, but I think how quickly it sharpens is amazing. I'm not saying S30V takes that long to sharpen, but 14C sharpens faster than some of my 440 knives, so even if I do get a deformation as bad as on my S30V knife, it won't take nearly as long to sharpen out. Plus it kind of creates the illusion of taking a sharper edge too since it's so easy to sharpen and strop.
I'll just put it this way... S30V is a great steel, and I don't see anything wrong with it. However, as an average consumer, if you offered me the same knife in S30V $25 more than the same knife in 14C I'd take the 14C in a heartbeat. The two perform so closely to each other that I don't really feel the need to nitpick, but I definitely like the price of 14C knives more so far.
If i had to actually find two contrasting points, I would say that 14C holds an actual razor's edge a little longer than S30V does before it dulls, but S30V's edge just keeps on trucking while coarse whereas 14C jut gets dulled out. So far I haven't really encountered the need for that gain in wear resistance and have been wishing my Kulgera came in 14C so I wouldn't have to worry about how long it will take to sharpen it if I hit a staple or something.