I have seen this as a prominent post who is better etc.... people fail to see where others don't point out the fact that Hexxat is immune to level drain, most other mind spells. She's a great undead killer. This is a huge advantage over, per se, Yoshimo (I don't want to have to cast negative energy and death resistance on him too; it kills my spell slots and takes my clerics time. She has 20str 20dex (vs yoshimo 17str 18dex natrually) when not in daylight (I will discuss that later) She has regenerate innate ability as well. So she's a better assassin, better marksmen and she is immune to death spells/effects, Negative energy, and poison.
Now to the cloak and day light. Soooo most fights in this game are done in dungeons / castles or caves / underdark. This means the about 10% of your fights (unless you are traveling to pick up gold or exp farming) is not so much a drawback, as much as it is a "OOOOOpppps I forgot to put the cloak back on poof dead vampire" The fact that she is innately immune to so many things I am going to have to place her over Yoshimo. This obviously is not an RP choice unless you are playing an evil character, but she is still a good choice overall.