They both have downsides. Guaranteed employment makes me think of absurd make-work programs (breaking and replacing windows or digging and filling ditches) because there simply isn't enough work to go around for the entire labor force, and 0% unemployment (as in "anybody who wants a job has a job") will be terrible for people who are hiring and need to expand their labor force. The negative economic distortion of a guaranteed income seems less severe than guaranteed employment, which would utterly screw up the job market, lead to massive inflation as wages skyrocket due to people having to raise salaries to attract people to new jobs, and probably slow the rise of new companies and lead to a more stifled economy.
While I tend to lean towards the side of guaranteed income I don't think that you would necessarily have to go out of your way to create bullsh**t jobs, there are plenty of roads and bridges which could use repairing as it is, not to mention things like solar panel installation.
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