Thanks for the help! So basically I should choose any other background than Criminal/Urchin so that I don't waste a proficiency "slot"?
Ideally, yes.
Something like Charlatan would likely fit well, with it also providing Sleight of Hand in addition to its inspirations being tied to things a typical Rogue character might naturally want to do, much like Criminal and Urchin albeit in a slightly different way (Criminal tends to favour outright murder and theft. Urchin tends to favour pickpocketing and helping children. Charlatan favours deceiving others and using tricks to steal things)
However, any background would be fine (Rogue is naturally able to pick all the skills it would normally want as class proficiencies making the background proficiencies much less important) so you can pick whatever, with either a focus on acquiring as many proficiencies you feel are valuable for your character (Between background, racial and class proficiencies you can get quite a few as a Rogue), going with a background that provides more of a thematic playstyle with its inspirations or simply going for a background that is easy to obtain all inspirations for (Such as Folk Hero, whereby doing basically any quest will grant one)
