Venom is the #1 trusted bushing brand. Hand-poured by the team themselves in the USA.
Legend has it, Zak Maytum used to pour these bushings in his garage and peddle them at races back when the scene was mostly Euro dudes on stock Randals and footbraking heavily. He worked tirelessly to make a bushing with tight tolerances and a solid center without sacrificing turn and lean.
Years later, the bushings are made en mass and are the top choice for pros. Don't believe me? Go to a race. check out a few set ups. Venom bushings. All around. Cannibals, everywhere. More than occasionally Rouges. It isn't because Zak is super cool and everyone wants to skate like him (though that's kinda true), it's because it's the best urethane formula in the game. They lean as much as you need and then return to center without bouncing you off. It feels like how trucks are supposed to feel. It seems obvious, and like you can't go wrong making the little thane donuts, but you'd be surprised. Since Venom took over, all the other options suddenly much less appealing.
If you're not riding Venom you very well could be doing it wrong.
SHR (Super-High Rebound) is a more springy and lively option than HPF for those who prefer a snappier return to center.
SHR is more suited for freeriding, cruising, dancing and freestyle than Downhill.
Here's what Venom says about them:
Super High Rebound (SHR): We started working on SHR in March of 2009. There seemed to be a demand for an insanely high rebound bushing, but there just didn't seem to be any good ones on the horizon. The problem was, the other super springy bushings on the market were only super springy. No damping. Cars have springs AND shocks for a reason! All the rebound with no control has a great effect on stability and adjust-ability. If you try to tighten your trucks with no damping, a lot of the time the bushing just squishes, and you get no more tension.