BEST STRINGS FOR DROP-C

I use graphtech stuff and have no problems staying in tune at all! The bridge saddles can be replaced with them and their slot is the same for all the strings so no going wrong there either. They even make saddles for different type bridges. For the nut I would take it to a tech so you get the proper fit and no string buzz.
 
I must like snappy high-tension. I had some guys in that tuned to C with 10's and it was just so floppy and loose, it just felt wrong to me; and like what JBroll was talking about, just seems liked there wasn't enough power. I would suggest upping the guage whenever your playing downtuned and note the difference.
 
I use GHS Boomers Light Top Heavy Bottoms for standard and Drop C. They're 10 - 52. They're really not that loose at all. I've been using them for years and won't use anything else after trying Markleys and Ernies. I have those plus a 70 on my 7 string to tune down to G and that thing is massive. That one string cost almost as much as the other six together. I pound the hell out of them and I've broke one string in around 5 years and I hardly ever change them unless they straight up need it.
 
The problem with those is that the low E is too light and the A is too heavy, and the problem is even worse in a drop tuning.

You can buy a GHS .070 guitar string for maybe three bucks at JustStrings.com - if you're paying more than ten bucks a set, you're paying too much. I would, however, recommend that you buy the GHS baritone set (14-70) and add a high 10 or 11.

Jeff