SIG VS HK generally speaking is a wash. The HK will be more robust overall owing mostly to the polymer vs aluminum frame and it will be more tolerant being run dry. SIGS should be run wet/greased. All steel SIGS are of course available but are heavy beasts and generally when talking SIG the gun in question is an alloy frame.
---Accuracy is a wash.
---Reliability is a wash. Well except HK guns will feed rounds backwards if necessary.
---Recoil is a wash
---Comfort is a wash and depends on user pref.
---Cost is close to a wash but a lot of the extra cost of HK comes from their R&D and quality control. HK in my opinion generally has exhibited better overall and more consistent QC then. SIG.
---Aftermarket no contest goes to SIG
---Magazine quality. Used to be a wash but since SIG started using Checkmate fore some of their products reports are not nearly as positive as the MecGar builds. HK mags are built in house and hell for stout.....and made of unobtanium and blessed by virgins and packed by Tibetan monks......hence there cost.
---Capacity SIG. generally platform to platform HK will be lower capacity or Sig has higher capacity options.
---Customer service. SIG has had much more consistent after purchase support than HK over the years. HK has supposedly gotten better.
---Controls are a wash/preference. I like how ambi HKs are and love paddle mag releases. Many hate them.
---Fit and finish. Edge to HK but nothing to bet the farm about
---Finish durability. HK. I don't think you could scrape the finish of an HK with a GLOCK. Seriously HKS finish is just like GLOCKS treatment.
---Trigger goes to SIG for TDA. HK LEM is better then DAK IMO. HK gives you a ton more options so they get the edge here. But feel for feel it's a wash really.
Honestly comparing a 220 or 227 to an HK45 comes down more to preference then actual superiority of product. I do think the HK warrants it's price as it seems to go to QC and controlling parts by not outsourcing but would that make a whit of difference in a real world civilian application? Probably not. How about a military application. Well since the SEALS are known to use P226s and HK45cs. Probably not.
At the end of the day plastic is easier to take care of and steel rails on steel slide is better then steel slide on alloy rails as far as durability and maintainence. There is your primary difference imo.
Shoot safe,
Chris