Most Quantitative Trading Desks (At BB S&T)?

In general, exotic derivatives desks are the most quantitative. Within exotics, I think rates exotics are the most complex (some of the stuff in this space is just insane - look up snowballs, ratchet caps/floors, target accrual redemption notes, etc.).

I believe that interest rate options, credit index correlation/options, and agency mortgage derivatives are also pretty quant, and are considered to be some of the more complex non-exotic derivatives (in fact, I think some banks combine these with their exotics desks into one large desk).

With respect to equity derivatives vs. FI derivatives, vanilla equity options are definitely more quant than the "light" FI derivatives (interest rate swaps, credit default swaps, etc.) and comparable with vanilla FX and commodity options. And of course exotic equity derivatives are just as complex as many of their FI exotics counterparts.