Inevitably, the best bolts are Onyx... seeing as they drain health and add to your own, but they require massive amounts of tokkul, Dragonstone tipped bolts run from 8-10k a piece, and they can be a drain on the bank, but if you cant or dont want to pay for those diamond bolts are very effective as well, i would still stick with diamond if your on a tight budget seeing as they hit well and are not as expensive.