Actually 'Our candidate is better than you' can be either Vår kandidat är bättre än du/ni or … bättre än dig/er. Both ways work in Swedish. In this case English is helped out by yours, but in a sentence like Jag är längre än han/honom, both ways work both in Swedish and in English: 'I am taller than he/him', so this often works the same in both languages.
än and than are grammatically ambiguous, they can be seen either as a prepositions or conjunctions here.
er is the second person plural possessive pronoun for an en word, as well as the second person plural objective pronoun.
If you were talking about an ett noun instead of a kandidat, you would use ert, or era for several candidates.
Our table is better than yours: vårt bord är bättre än ert
Our apples are better than yours: våra äpplen är bättre än era