Go for nekro. If you PvP, mark my word, it is almost impossible to play without Nekro. The rogues will just crit 2 shot you (why the hell is rogue critical so strong? I have almost 10K health and I got 2 shotted, well anyways). At LvL 61, warriors can get around 5K+ armor so MM is somewhat redundant, SnS has a pretty good AA, but difficuot to use efficiently in PvE and PvP. SnS is more of a clash type of pet. Nekro, in return, grants shield that gives you massive 40% damage reduction like Jazzi said, and stuns enemies.

Overall, even though many people have Nekro, it is by far the best pet for all classes.