I've shot the HK Match, Elite & Expert in 9mm and the Expert in .40. Also the USP 9, USP 40, USP9SD, & MK23.
I've shot the Glock 17L & 34, I've not shot the 24. I've also shot the 19,17,21,22, 27, 35 & 31. I qualified for the Australian IPSC team with a G17, FWIW.
I've no experience with those Sigs, have only shot the 226 & 220. I'll defer to Morgo on the relevant improvement of the match grade Sigs over the Glock & HK.
Between the Glocks & the HKs, as a static, down the line target gun the HK Expert & Elite rule. The O-ring barrel does add accuracy. Downside of these guns is the relatively crappy trigger vs 1911s or even a well done Glock trigger. Sights are exponentially better than the standard Glock sights. the gun does tend to jump around more under recoil, being light weight with a higher barrel axis than the Glock. I'm not a fan of the paddle mag release and found that the ambi safetys would hang up on the flesh of my palm.
The Match was simply a range toy - the guys who bought it thought it looked cool in Tomb Raider. If I knew they were going to go up 4 times in price I would have bought one too! Apart from looks and cost I really didn't see any difference between it and the standard USP.
I had a friend who shot the Expert in IPSC as an A grade shooter. He swapped to an STI 2011 and broke Expert at the next match. The USP platform is a limitation at the higher end of run and gun games.
If you plan to run and gun then the Glock 34 is probably a better platform, as there are a plethora of aftermarket triggers and sights. The standard trigger will wear in quite well anyway. The G24 & 17L will be excluded from some matches though as the long barrels puts them outside the rules.
If I was going to buy guns out of your group then I would gravitate to the Sigs because a) I've yet to try them, b) They have an excellent rep and c) I am aware of the drawbacks of the polymer guns in competition shooting.