I've pretty much narrowed my choice for my next gun down to a .45, and the two which stand out most to me are the Glock 21/41 and HK45 with LEM trigger.

 

I'm looking for feedback on the "shootability" of these two guns, which I'll define as the cumulative effect of various traits which enhance or worsen the interaction between shooter and gun during the firing process. Any hands on experience with either gun is hugely helpful, positive or negative.

 

For the sake of this discussion, price is irrelevant.

They're very different guns with different grip angles, ergonomics, action, trigger feel.

 

HK trigger feels a million times better than a stock Glock will.  HK's are also more accurate out of the box than Glocks.  

 

It sounds like I'm pissing all over the Glocks, however I still shoot my Glocks about 20x more than my HK's.  

 

I really suggest shooting both and deciding what feels better in your hands.

In my view the HK45 is a better shooter. The G21 is not bad, the HK is just better. The LEM trigger may take some getting used to since 3/4 of the takeup is 'loose'. You also have to be OK with the paddle magazine release. I agree with Mikey; you really ought to shoot both before buying if you can. 

 

However I'd add one more strong candidate to your list: PPQ 45. I haven't shot one yet, but if the trigger is anything like the PPQ 9mm, it is good. Perhaps the best. That one's on my buy list.

I agreed with 45Doll, add the Walter to the list and try it. I was raised on a 1911, enjoy the G21 with modified innards. but the Walther is on the short list.

Since I own and carry my 21SF, I didn't buy the 41, but if I didn't own the 21SF, I'd get the 41 maybe even MOS.

I think you should try the high point 45. Excellent. And fail safe at a value.

Get a Mark 23.