Re: Sh-5 or Jb in strat bridge?
For straight-ahead hard rock/metal tone, and not much else: JB. The pickup cuts through and stays together even at high volumes and high gain, because the bottom end stays tight. It's not the brightest pickup, but it does have a lot of clarity due to that cohesive bottom end at high volume. The 250K pots in most stock Strats will mellow it out a bit on the top end, which you may or may not like. I prefer it with 500K volume pot, personally.
For versatility: SH-5. It covers more bases, though I would say it has a less "flamboyant" personality. Brighter than the JB on the top end, but also looser on the low end. Doesn't hold together as well as the JB at high volumes/high gain. This pickup does fine with the stock 250K Strat volume pot IMO.
I'd probably make my decision based on the amount of volume and gain I was using. If using more gain, or if I used a lot of pedals for dirt, I'd go with the tighter bottom end of the JB. If not playing as distorted, more of a natural "clean crunch" tone, I'd go for the Custom.
I'd also be more tempted to go for the JB in a 2xHB guitar, and the Custom in an HSS guitar. It's nice being able to flip the switch to take a break from the JB, yet still have the humbucker sound. The Custom blends better with Strat singles IMO.