what is more valuable: a front end developer with some ux knowledge or a Ux designer with some development knowledge?

There is value for any specialization to have knowledge on concepts important to peripheral specializations. When devs and designers share greater understanding of what the other does, they can collaborate as a team more effectively. Many of the resources front-end devs consume for learning and practicing will overlap to an extent with UX concepts, so it isn't even really possible to avoid them if you want to excel in the field. Designers, on the other-hand, usually need to go more out of their way to get exposure to web development beyond some basic HTML and CSS. Because of this, I find that good front-end devs more often make up for the communication gap between dev and design, since they will organically learn more about design in their day-to-day.

If your goal is to get a good job, given those two options, I think going down the front-end dev path is easier (assuming you enjoy the work enough to learn the necessary skills) because there is relatively more demand for that skillset.

Neither. Specialize and niche down. You already have so much to learn and get good at that trying to do that for both will never work out. A front end DEV needs ZERO ux skills and a ux designer needs zero development skills. Are there companies that try to cheat the system by wanting that unicorn? Sure, but theyre also the companies you want to avoid with a ten foot pole. Especially when there are many that respect and understand that the roles should be kept separate.