My preference is for the standard pressure Federal HST in any of the common calibers. Gold Dot is a proven round, along with the hard-to-find (and thus somewhat cool) Win Ranger T/Bonded and I've carried both in the past. Yet the HST is a newer design, widely adopted by law enforcement, plentiful and cheap ($25/50 in 9mm). It's also by far the best performing round in the tests I've seen.
Across the board of calibers and bullet weights (excepting .380, which is
kind of a crapshoot anyway) the HST is far more consistent than even the Gold Dot and WAY ahead of the rounds marketed as "self defense" ammo. By that I mean Critical Defense/Duty, PDX, Remington Ultimate Defense, etc. which perform in a range from 'decent' to 'absolute garbage'. Decent might be the .380 Critical Defense, which is one of the better rounds in that caliber, while absolute garbage might constitute the failure to expand, under- and over-penetration and core/jacket separations seen in so many of the tests below:
http://www.luckygunner.com/labs/self-defense-ammo-ballistic-tests/
This experiment, while not as scientific as Dr Roberts', nonetheless has a fairly throrough and convincing methodology (lots of expensive gelatin, controlled conditions, 4LD, etc) and is well worth reading as raw material. There's not a lot of analysis but pay attention to penetration depths and expansion, both in the chart and the pictures. In this test, the HST opens up big every time and penetrates with remarkable consistency. There are some rounds that come close or exceed it in SOME loadings but by far the HST is the most reliable across the board, again that's in
this test.
Would you rather carry a 124gr 9mm HST that penetrates 18.3" and expands to .61" or a Critical Defense that penetrates 13.1" and expands to .50"?
While the latter is better than the Golden Sabers that completely fail and separate (how anyone can trust their life to big green is amazing), or the exotic stuff like RIP that's completely unproven and, IMO, pointless to carry, I think it's important to trust your loading implicitly. I'll add that sticking with the most common bullet weight for a caliber (124 for 9, 180 for .40 and 230 for .45) is best, as are std. pressure loadings. You don't need 147s for winter and you don't need +p for expansion...if it makes you feel better fine but the regular stuff is gtg.
I certainly wouldn't want to be shot with any of the above rounds but Federal has spent a lot of time and money engineering the HST to perform exactly as law enforcement wants. There's still a lot of love for Speer and their position is quite established, the 'gen 2' Gold Dot was not a winner out of the gate but the original round is still good stuff and I'm sure that Winchester has a piece of the action in some departments too.
It would be interesting to know the loads that some local departments carry....anyone care to chime in on what the Staties feed their M&P 45s with?