But if you don't already own any lenses, you really can take you pick based on either lens choice or body choice, I reckon. At the consumer level, both camps have some very nice lenses. Arguably there's slightly more choice available in the secondhand market for Canon mount lenses, but not everyone would agree I'm sure.
Maybe if you're going to be using professional level long lenses - like those giant white beasts you see around the edges of football pitches - then you might choose based on a preference for a specific lens... but if you're talking about those lenses I would expect that you would not be deciding between the XTi and D80 (unless you've just won the lottery and plan to buy it all anyway!).
