The Duncan Little '59 and JB Jr. come to mind. I like them both and actually prefer the neck model JB JR. used as a bridge pickup. More highs and enough of a boost in output compared to a vintage Strat pickup to satisfy me.
I found the Duncan Hot Rails to not have a tone that was right for me but it was the strongest and pushed my amp the hardest.
I've used them all. I have a hard time recommending something other than a Duncan pickup on Seymour's own forum. Let me say that my buddy AJ has a Jimmie Vaughn Strat and I put a Duncan SSL-1, Duncan SSL-1 RW/RP and a Fralin Steel Pole 43 in that guitar. I really like how ALL of the pickups in that guitar sound - individually and combined.
If you're after the tone of a full sized Gibson style humbucker, no single coil sized Strat pickup will really get 100% of that tone and overdrive.