A lot of IDEs these days offer a three-way-merge interface that massively improves on the conflict resolution process. Different tools have different interfaces, but generally you have three panes visible: one showing the diff original->A, one showing the diff original->B, and third showing the current state of the merged file, without conflicts. You can typically add chunks from either of the two diffs, or free edit your resolution based on a combination of the different options.

I find resolving conflicts through this sort of system tends to be a lot more intuitive than trying to mess around with conflict markers - it also helps with protecting against mistakes like forgetting conflicts or wanting to undo changes. If you're not used to it, I really recommend finding a good three-way merge plugin for your editor/IDE of choice.