I often ask myself what gear is the best when playing solo.
Most people advice for berserker or marauder gear.
For many professions, critical hits provide additionnal numerous bonuses or are simply necessary to success.
As an example, Berserker specialization get might on critical, and furious can get you some adrenaline. Plus, you absolutely want to critical when using your burst skills.
Berserker: 60%, 80% with fury
Marauder: 70%, 90% with fury
Assassin: 80%, 100% with fury
Granted you can improve those numbers with sigils, runes, and food, but it will add strong constraints to the build.
Assuming you can have perma fury, Assassin seems the best as you can have perma critical hits.
Marauder is not far behind, but still, 10% counts and you would need Sigil of Accuracy at least. Leaving you at 3% less than Assassin, not bad but locking down one sigil for both weapons set.
Berserker seems really low and I can't see how it can perform nicely, even with food, sigil, and rune help. And even if you could manage a good number, it would probably shut down any food/sigil/rune choice. And those are particularly important in solo situations.
Berserker/Marauder higher power is meaningless if you don't make critical hits when needed.
Conclusion: I think Assassin is the best if you want to freely choose sigil, rune, and food. Marauder comes second, it will definitly lock down some choices.
Finally, Berserker seems to be only good for group situation when others will bring your critical to the max.