JMOfartO:
From my experience with 3rd gen Smiths I think you might be "going away from home" choosing the 5906 if you are planning on using it primarily for "informal plinking and casual target matches.
First let me say I'm a big fan of 3rd gen Smiths (I have a 3913/3913LS/6906/CS9/5906), but lets be honest here, fantastic accuracy is NOT a known strong suit for these pistols. I'm not saying they aren't accurate, because they certainly ARE self defense accurate, but imo the strengths of the 3rd gen line of pistols is RELIABILITY and overall performance rather than offering the potential for making the smallest group of holes in targets such as you want for your pistol choice to be capable of.
Crap, if you want small groups buy a surplus Lower Saxony Police HK P7 for around $600.00 and it'll be more accurate than are capable of taking advantage of.. You'll be amazed at how your marksmanship has improved once you pull the trigger on a fine HK P7..
In the same vein, the Walther P99/AS, or SW99 will both shoot circles around the average 3rd gen Smith.. And keep in mind when I chose to cc a 9mm pistol it's generally one of my 3rd gen Smiths, so I take no pleasure in knocking any aspect of what I personally consider to be some of the finest pistols ever made by Smith & Wesson.
I use my 5906 as my home defense choice as I have found it to be as reliable as any firearm man-made can be.. It has good capacity at 15+1, and the CT Lasergrip makes it a tack driver at self defense range... I think the home defense role is perfect for the all steel, heavy, 5906.
You've said you want either a 5906 or the Glock17 as your only choices so, and I hate Glocks, I'd say go with the Glock17. I've had a couple of Glock 26's in the past, and even though I hate the Glock trigger/striker, and even tho the Glock 26 has the grip ergonomics of a brick, they were very accurate..
I've read where the best way to improve the 3rd gen Smith accuracy is to have the barrel recrowned.. Don't know as my 3rd gen Smiths are sufficiently accurate for my self/home defense needs. But anytime my buddies and I want to go "out back" and try for the smallest groups for braggin' rights I take my P7.
My buddy's casual target plinker is his SW99. We've shot the SW99 and my Walther P99/AS head to head and accuracy was excellent on both.
SW99's are being sold every day at very reasonable prices at CDNN.. If you are talking straight accuracy IMO there would no comparison to the potential accuracy in the SW99 and the 5906. I'd be willing to bet the SW99 will shoot AT LEAST as accurately as the Glock17 you are considering.. Better grip too..
I know you didn't care for more pistol suggestions, just a choice between the Smith & Glock, but I'm old and semi-senile with short term memory loss, so I'll forget I offended you pretty shortly anyway..
But if you are talking JUST accuracy, there are many better choices than the fine, reliable and quality built 5906..
The best way I've found to get small groups with my 5906 is watching the red dot coming from my Crimson Trace Lasergrip fall into the X ring. If you expect real good accuracy out of a 5906 best invest in one..
IMO
Best Wishes,
Jesse