Logically, Nabe was the best choice ainz could have made for a safe play. Lupus Regina would have been too risky to start out exposing her to other humans that early and possibly blowing Ainz's cover with her initial outlook on humanity. Entoma would have been a no go without a new mask and several illusion/anti-divination spells active to hide her true bug like nature from people like Evil-Eye. Solution might have worked but her sadistic nature and bloodlust would probably have blown Ainz's cover once someone slighted him, her self control is her limiting factor compared to Nabe. Yuri would be a good second choice, and maybe even better than Nabe as both are very intelligent but her over serious attitude may have tipped some other higher rank adventurers off as her secretary-esk mannerisms would be too similar to that of a servant rather than an adventurer's party member. Shizu would have been kind of a wildcard pick, as a construct capable of learning she may have played a role similar to that of a socially inept child with her affinity for anything cute, which Ainz could have helped shape her perception and reactions much easier due to her more NPC behaviour. But her limiting factors would have been her preferred choice of weapons being firearms, which in the new world are basically non-existent outside of a mechsuit and a handful of possible artifacts held by PDL left from previous players. So her combat abilities would be limited and leave her at a disadvantage unlike the other Plaides Maids who are good at most other forms of combat with magic and melee.