What are the benefits and disadvantages of CBC vs. CTR mode? Which one is more secure?
I wrote a rather lengthy answer on another site a few days ago. Bottom-line is that CTR appears to be the "safest" choice, but that does not mean safe. The block cipher mode is only part of the overall protocol. Every mode has its quirks and requires some extra systems in order to use it properly; but in the case of CTR, the design of these extra systems is somewhat easier. For instance, when compared to OFB, there is no risk of a "short cycle" with CTR.