Don't post here much as I don't usually have much to contribute, but in this case, I too have both. I have a 3-15 Conquest with the lock plex turrets, and a 6-24 HST (same glass as the PST, but with a wire reticle and no illumination).
I had the Conquest first, but when I was looking for a scope to put on my range rifle, I looked at both the HD5 in a 5-25 and the HST. I won't go into the details, but long and short, glass wise, especially at top magnification, Conquest wins, especially in low light. Even my 3-15 x 42, at 15, bests the HST, which is a 50, in low light, but not hugely as I remember.
This is important to note because I was testing 15 power vs 15 power, so the HST was in the center of its mag while the Zeiss was at the top.
When you dial the HST to 24 power, it really loses resolution. Both Zeiss's do much better, holding clarity at top mags.
As I remember, I believe they also have about the same adjustment...my 3-15 actually has 75 or 79 MOA, can't remember, while my HST has 70 ( supposed to have at least 65).
So why did I guy the HST instead of a 5-25 Zeiss to go with my 3-15? I would say it depends what you are going to do with the scope.
If it's for a hunter, I choose Zeiss. I have it on my 300 win mag because it's low light capability is better, I like the range better for hunting, and most of all, I like locking turrets. No worries about bumping the turrets etc.
But I bought the HST because I don't like Zeiss zero stop. It limits you to one turn. So on the Zeiss, I am good for something like 750 yards or something like that. Fine for my hunting rifle, I am not good enough to shoot even that far.
But my range rifle, I need to shoot farther, so I had to disable the zero stop when the zeiss was on it. And I didn't like that.
As for the low light, not that important for me at the range.
Loss of clarity at high mag? Yeah, but my particular one is very good up to about 18 or 20 power. And not at all unusuable at 24, at least for me in regular light (except for mirage problems, but that' probably equal). It's just not as good as it could be, but for shooting steel, more than good enough as long as you are not trying to shoot in low light, though to be honest, I have not tried to shoot really long in low light. I just set it up at night and compared between the two at various mags and found the HST definitely wanting at top power, and this was more obvious as the sun went down. Maybe it would be fine for you, but in my experience, the Zeiss was definitely superior here.
Good turrets, seems repeatable, fairly nice optics, good enough zero stop, and decent price. So for this use, HST.
But for a hunter, if having only one turn is enough for you so Zeiss's zero stop limitation is not a problem, the lock plex Conquest is great because the optics seemed better to me, and I love those locking turrets.
Hope that helps!
