I highly recommend the Loft01! (and I believe all other Lofts from Alejandra should be great options)
The place looks great, exaclty as in the pictures. It was clean and tidy when I arrived.
The self check in was super easy and flexible.
Alejandra was super friendly and available for any question I had.
The location is farther from the city center so note that you will have to commute or walk quite a bit but it is so worth it for the comfort of the place. Stops for bus 28 and 62 are nearby and will take you to the city center in +\-20min.
The neighborhood is calm and felt safe. The big windows from the kitchen give directly onto the street but there was not much traffic so it doesn't get too noisy.
If you come as a group, note that the two bedrooms and the living/kitchen area are one big open space (although both bedrooms are visually separated by the bamboo walls).
The kitchen has all the utensils necessary (I just really missed a cutting board) but there are no ingredients at all. So know that you will have to buy/bring even the most basics (oil, salt, etc.) if you are planning to cook. Same for the washing machine soap.
The wifi worked great, the bed was super confy, the bathroom had everything you may need.
Honestly this is a great option, especially for longer stays in Valencia!
Hope you enjoy it as much as I did :)