> (I know if they have more hp and AC then I do, but other then that).
That's not an entirely fair comment for the guardian. If you are only comparing ac/hp to another potential tank with their ac and/or hp being greater than yours your choice on who tanks should not be because of a minute difference in ac and/or hp. You should take into consideration skills/abilities that your guardian either a) has or does't have, b) what sort of tank you are comparing to, c) prolly a bunch more but those 2 really jump out, although level would play a major role as well, but a 1 or 2 level difference I would think should not.