I like both guns but I would say my favourite just for how fun it is to use would be the Ballista.
The random above waist hit-markers are an issue but it just feels so manoeuvrable and fun to use if you're trying to get multi-kills.
I'm fairly new to sniping, BO2 is the first COD I have put any real effort into learning the snipe mechanics and I like to just chill out and play FFA with the Ballista, I very rarely win my match (unlike if I run SMG) but hey ho, I have fun playing and that's what it's all about.
I cant touch the SVU or XPR though, those guns just suck.
honestly not a big fan of eather. ive always loved snipers but on black ops 2 i just cant snipe at all im about average. i prefer the ballista for qs and the dsr for long ranged fights but all in all i prefer the xpr over all of them. 1 shot kill + its semi auto so if needed i can take out multiple enemies without the annoying bolt action call me a noob but i find firing off shots rapidly more effective than ur traditional sniper on games who likes to do trick shots and shit i play to win not do fancy tricks so ya i can qs and ya i do hard/drag scope only thing differant than ur average camper sniping is im a rusher i cant stand sitting still it bores me to death so i rush around sniping qs hard scope ext. w.e gets the job done but ull never see me no scopeing >.<
I usually switch up between both snipers but if I want to be aggressive than I will use ballista or If I'm rushing but kinda keeping my distance/mid range I use the DSR it basically depends on what map your playing on.