I never purchased a revolver before...
Since they are both large and clunky, might as well have the double action option.
Yes, both are big, heavy guns (48oz+/-) Essentially, the 7.5" Ruger weighs the same as the 6.5" S&W, there will be minor weight variances between individual guns, primarily from small variances in the density of the wood grips.
If there is a chance you may be hunted (bear) I would vote for a double action weapon, I don't want to try to cock the hammer on a single action when I'm fighting for my life.
There is this, but it only really applies if you and the bear get belly to belly close.
It also depends if you are going to run stock ammo or if your going to step up to more +p type ammo,
Recognized +p ammo in .44 Magnum does not exist. There is no SAAMI spec for +p in the .44 Magnum. There is only ammo that is within SAAMI spec (pressure) and ammo that is outside SAAMI specs. Outside of SAAMI spec ammo can be called anything the maker wants to call it. It an range from "just a little warmer than factory" to "wreck your gun stupid HOT!!"
It all depends on the maker, and how much you trust them. Hot stuff from the smaller "boutique" ammo makers will tell you what guns you can use it in, and what you should NOT.
Ammo in a baggie, bought at a gun show, loaded by Mr Nobodyhasacluewho, is always a risk, no matter how good the price.
I have a 7.5" Ruger Super Blackhawk, a 6.5" S&W m29-2, a 6" Desert Eagle, and a 10" T/C Contender. And over 30 years experience shooting them. (ok, only 26years for the Desert Eagle .44..
)
The OP said "I've never purchased a revolver before". So I would assume he is not a skilled DA shot. He also said he has a .44 Mag Marlin, so he knows about the recoil of the round, in a rifle.
In a handgun, its a much different matter. Grip shape is the other important difference between the SA and the DA revolver. At .44 mag recoil levels, it makes a HUGE difference, especially to a new 44 pistol shooter. And, it's a completely PERSONAL decision which type feels better.
The classic "plow handle" SA grip is designed to allow the gun to roll up in the hand during recoil. The DA revolver grip shape is designed to prevent that. That means nearly ALL the force of the recoil is sent straight back into your palm and arm. Less muzzle flip, more jolt to the hand.
For me, the S&W with stock wood grips is painful to shoot with full power .44 Mag loads. Literally, it hurts. I have Pachmayr grips on both my S&W and my Ruger. Again, for me, they turn full house loads from painful to uncomfortable (S&W) and from uncomfortable to stout, but tolerable (Ruger).
I think that how the gun feels in the hand, and how it bites, or doesn't during recoil is more important to a beginning .44 shooter than DA or SA firing.
Just FYI, the most mellow recoiling .44 Mag I know is the Desert Eagle, because the huge pistol weighs so much (4.25lbs EMPTY).
The sharpest is the Contender, because even with a 10" barrel, it's still lighter than a 6" revolver. First time I ever fired mine, the barrel flipped up so much I said a bad word, out loud (rather loudly
,). at the range. For pure "visciousness", I got to shoot a friend's Lew Horton Special (S&W M29 short barrel (2.5?) round butt). It had Pachmayr grips.
With his pet loads, it wasn't bad. With a full house 240gr handload, it not only kicked like a mule on sterioids but it twisted in the hand until it was "gangsta" sideways! (serious TORQUE!!)
Considering your (assumed) experience level, and the fact that you are going to be hunting (which is quite different from defending yourself) I would go with the Ruger SA, in your preferred barrel length.
I would also recommend some .44 Special ammo, and some .44 Mag loads that are lighter than the hot 240gr jacketed stuff and work your way up to the max loads. Silvertips are nice step on the way up.
IF at all possible, SHOOT both type of guns before you buy. Range rental, friends gun, stand around the range looking wistful, offer to pay for the ammo, whatever it takes, if possible.
The difference in the feel of the SA and the DA at .44 mag recoil levels is tremendous, Some folks are ok with either, some find the cannot stand one of them, so, getting at least a little shooting experience with them might keep you from sending several hundred dollars down the wrong road.
Good Luck, and let us know what you decide!