If the floor plan works for you, that's all that matter.
A deal killer? Something you definitely do not like, want or need.It could be the interior color or the lack/presence of a washer-dryer. It's up to you to decide.
A must have? Something you can't do without, like a washer-dryer, exterior television, second toilet, etc.. Again, it's up to you and your likes or dislikes.
Two vanity sinks? That could be a deal breaker or a must have.
Bottom line, find what you like. When buying used, condition is the important factor. If the unit is in good condition, the price is right and you like the interior, you may have found the one for you.
Enjoy the search.