Silicone based lubes are typically the best for anal because they last longer and tend to be slicker than water based kinds, they're also condom compatible (A quick note here about anal and condoms- you should still use one even though there's no risk of pregnancy, the tissues in your anus are really delicate and there's no natural lubricant to help clean out possible infections/germs. Plus, those condoms designed for extra sensations for Him may be even better with such a tight fit). I've used Pjur backdoor and while it's consistency is good, the jojoba oil for 'relaxing' the area gives a very peculiar sensation that's not quite warm or tingly or anything, just present and unwelcome. For some women, that's WAY too much. So if I were to pick a product I would definitely say the Pink Silicone Lubricants (available on this site). They even have Vitamin E and the design of the bottle looks discrete and feminine.

I'd suggest checking out the System JO products. Their water-based lube has a silicone-like feel to it, and lasts quite a while.