I see this sort of question as more likely being affected and influenced by the experience and personal preferences of the owne/user, myself ...
Very few medium bore revolvers feel and balance as well as a K-frame. Excellent guns. Close to being the quintessential medium-size Magnum revolver. Power balanced against carrying weight ... and what I refer to as a 'lively balance' in the hand, while still retaining some reasonable heft, when it comes to K-frames.
Unfortunately, the day of the K-frame chambered in .357 Magnum has finally passed. It had a much longer run than the excellent Security/Service/Speed-Six series, though.
I do find it a bit ironic that while S&W discontinued the K-frame chambered in .357 Magnum, standardizing on their L-frame for that caliber, they offered the J-frame in .357 Magnum in an increasingly varied number of models, including the interesting M60 5".
Mixed messages, so to speak. (I know, one makes for more comfort for shooting frequently and makes for more comfort when carrying frequently.
)
I really wanted a 3" SP-101 at one time. Couldn't find one and settled for a 2.25" DAO model. It served me quite well as a small Magnum revolver, including some service as a "off-the-paved-road" off-duty weapon for some backcountry activities from time to time. Handy. Lighter and easier to pack around than any of my Security/Service/Speed-Six guns, or my issued 686.
Still wouldn't mind having a 3" SP-101, though.
Why? Because I once owned a 3" heavy barrel M36 with which I shot almost as accurately as with my issued M686 at that time. Nice balance. Slightly longer sight radius. Better than expected practical accuracy and controllability ... albeit only with .38 Special ammunition, of course. Nice little belt gun.
I think the 3" SP-101 would make for a fine compromise when it comes to lawful carry and backwoods portability with a compact Magnum revolver. Granted, it can be a handful when chambered in full power Magnum ammunition ... and I finally had my SP-101 Quad-Ported to change its character when shooting Magnum loads. Tamed it quite noticeably when it came to muzzle rise/whip and torquing of my wrist, although the force directed back into the palm of my hand naturally remains.
Porting comes with both advantages and disadvantages, though, and is another subject in itself.
If I were going to consistently be doing a lot of shooting with Magnum ammunition I'd probably opt for the heavier iron-sighted GP-100 3". The extra weight would make for more pleasant shooting sessions, especially if extended duration sessions are common. More weight on the hip, though, and the point where that's counter productive for the intended lawful outdoors purpose has to be determined for each individual.
The SP-101, on the other hand, may be a bit more taxing and tiring on the firing line, especially for extended range sessions, but it would also be a bit lighter on the hip.
Compromises.
As far as workmanship and maintenance?
I've had to have both Ruger and S&W revolvers repaired.
I agree that Ruger revolvers are more easily disassembled - to a reasonable point - for cleaning, especially if subjected to extreme environmental conditions.
Their triggers may not have the smoothness in DA or the crispness in SA of a S&W, but then I long ago made the determination for myself how far I was willing to compromise for a rugged, durable, easily maintained 'field gun'. My Ruger DA/DAO revolver triggers are fine for my needs, and I don't notice much, if any, of a difference in practical accuracy when shooting them DA compared to my S&W revolvers. My S&W's have better SA triggers, granted, and I can generally wring some small degree of better accuracy when shooting them SA in a relaxed, unhurried manner.
This is one of those areas where a couple of knowledgeable, reasonable folks might reach entirely different decisions, though, both of whom having carefully considered their needs and desires before making informed decisions ... and both of them may still have made the 'right' decision for themselves.
That being said, I'm presently considering picking up an old 'beater' K-frame in either .38 or .357 Magnum, because an old friend who builds excellent revolvers, and has some time on his hands now that's he's retired, just told me that he's been asked to make a small number of PPC-style revolvers, using Douglas barrels, and asked me if I wanted him to make me one for old-fashioned range enjoyment. Gee, let me think ...
