I know, it’s an older conversation and I’m a newer member
Still…
I’d strongly suggest if you’re getting a stockpot to make stock you should consider a pressure cooker. Put a different lid on it and it’s fine as a conventional stockpot but cook under pressure and your stock is made in a third the time.
I have a 10 quart model, and a twenty five year old sitram 12 quart sitting unused for a decade.
Conductive sidewall pans provide more complex convection currents at stock- making temperatures. They also cool stock faster in an icebath.
Given your candidates, I would save a buck and go with the Lagostina.
I know a large number of cooks swear by this method. I do not have a pressure cooker, but for me the advantage of speed is not needed for stock. I often have a stockpot on the back burner either all morning or all afternoon. It takes no attention. So I already have available stock. I suppose the speed factor would be great if you needed a particular type of stock you did not have for a specific dish. Shellfish stocks or fish stocks are much less likely to be on hand in this house, and there are some dishes for which they are essential. Have I just kick started the process of considering a pressure cooker?!
I’ve got small, medium and large pressure cookers, all “jiggler weight” style. The middle size one is new, as it is compatible with my induction burner/hob. I still like my older smaller one, even though controlling the cooking process is more difficult on a radiant style burner/hob. I’ve cooked all manner of dishes in them. I haven’t made home made stock, but I imagine a pressure cooker would make quick work of the job.
The one I use for stock is this guy, 10 quarts. I’d never use it for fish stock, that’s a quick process and I’d be more worried about over extraction. I cook chicken for 75 minutes and beef/veal goes 3-4 hours.
I think this new style valve is a little more idiot proof than the jiggler, perfect for me!
After it’s done I fill the tall containers with the strained stock, let the fat rise in the refrigerator overnight and then I reduce by about half and put the reduced stock in the little Rubbermaid containers. Best ever investment was buying a label maker, keeps everything organized.
Cote du Rhône is not officially part of the process, it’s just shown for scale
If you often make fish stocks that you want hearty, this large French food mill (I think it’s tellier) extracts all the goodness from the fish head and bones. Mine is tin, not stainless so you have to hand wash it but I only use it a couple of times a year, no big deal
Switched to white wine for fish, and a black swan
How much muscle do you need to operate it?
Depends on the fish. I steamed some 1 1/2 pound striped bass and used the bones for stock, they were okay. You get the frame of an eight pound fish in there, your biceps 
will be bulging
You’ve always wanted a duck press for these anyway…
And…lest you need another reason, a SS PC bottom can be useful for brines and pickling.
Wouldn’t the salt in the brine cause the stainless steel to pit? Or are you talking about using it for canning?
. A duck press for the few times a year I need shellfish stock…hmmm. I am out of space! Saved by too much copper!
My tinned steel items like moulds, mouli, and chinois get dried on low heat in the oven to avoid rust in the nooks and crannies.
It depends on the alloy, the salinity and the duration. I wouldn’t ferment kraut for 6 weeks. Overnight soaks of chicken and turkey haven’t pitted anything of mine.
It also depends a lot if your brine contains undissolved salt. Pitting is a stochastic process, but put solid salt in contact with most any alloy, and you’ll get pitting.
Now then, I have had induction bottoms pit, but I attribute that to the 400 Series SS that is required to “work” with induction. If you use that for the exterior, by experience is you’ll have pitting. That’s why makers put it somewhere inside
Dunno, i think it’s pretty common advice to only add salt to a hot pot
Common advice not commonly understood…
