This isn't the wrong forum, but there is a better forum to talk about traditional slipjoints, and that'd be the Traditional forum. If you want, click the little triangle under your post and request it be moved there.
As for your choice between the Case Sway Back Jack or the GEC #15, honestly, you can't go wrong either way.
The SBJ is one of the best regular production knives Case makes. Any of the Case / Tony Bose collaborations will have a higher level of refinement than their regular knives. Better fit and finish, better dye jobs, better "walk and talk", etc. The chestnut bone/CV steel model is easily one of the most loved slipjoints here on BF.
IMO GECs are the best production traditional knives out there. They're made mostly by hand and in small numbers, and use top-notch materials for the handles, which is why they're more expensive than most others.
Although the Case/Bose knives are great, you're more likely to get a knife without issues from GEC. And while I haven't really heard much bad about Case's warranty service (lotta good, mostly, except perhaps turnaround time), I'd put more faith in GEC's simply because their comparatively tiny operation means you'll get better attention. Plus, all the dealers that sell GECs are all excellent and will go the extra mile or 2 to make sure you're happy.
Comparing the 2 knives themselves, there'll be a fairly substantial size difference. It might not seem like it look at specs on a website, but there is. The SBJ is a small knife. Not Peanut small, but still small. It's a 3 finger knife. The #15 will fill your hand, or at least most of it. Although small, the SBJ has a good heft to it. It's small, but not dainty. The blades are flat-ground, rather than hollow-ground like most Cases are. The SBJ fits in a pocket - even a change pocket - wonderfully. The #15 is by no means a large knife, but it'll be more noticeable in the pocket.
Since you're comparing the SBJ to the #15, which is only available in 1095 carbon steel, I'll assume you're thinking of the SBJ in chestnut bone and CV (modified 1075 carbon steel). Both will be pretty easy to sharpen and hold an edge fairly well. The Case CV steel will be a bit easier to sharpen, but the GEC 1095 will hold an edge better. Both, you should know and understand, are NOT stainless steels. If you use them to cut up an apple, the blade will turn colors and turn from shiny to a dull grey, with weird silvery blues. This is called a patina, which is a layer of oxidation. On steel, a patina actually protects the steel underneath from red/black rust forming (not completely, but it helps a lot). Some consider a patina ugly, but some consider it beautiful. Either way, using a carbon steel knife requires a certain amount of upkeep. On the Case, only the blades are carbon steel. On the GEC, the blades and the springs will be carbon steel (maybe the liners too, I don't know, the could be nickel silver).
If you want to keep things shiny, you need to keep everything oiled. Mineral oil is the typical stand-by (look in the laxative section of your pharmacy...trust me), as it works well and is food safe. Other lubes/protectants work good too, but stink and taste bad and might be toxic. If the blades darken or a patina starts to form, an abrasive polish like Simichrome or Flitz will bring the luster back.
If you don't mind a patina forming, just oil the joints once in a while, and make sure the blades are dry from water, or else black spots and/or red rust might form. You can let a patina naturally develop over time and use, or you can "force" a patina. There's a few ways of doing this. A common method is to stick it in an apple or potato and just let it sit. Repeat if necessary. This will give you a patina that starts out splotchy and with weird colors, but with repeated use and time will even out to a fairly consistent dull grey. Another method is to use a liquid that's acidic, like mustard or vinegar. Wipe on, let sit, wipe off, repeat. For a dark, even patina, heat up vinegar over a stove and dip the blade in it.
If you don't want to deal with any of that, then the SBJ is the only choice out of those two. GEC does make some knives in stainless steel, but very few, and not in the #15 pattern.
Frankly, I think everything I just spent an hour writing is going to be moot and pointless anyway. Whichever knife you end up buying, you're going to long after the one you didn't, and eventually end up with both. And that's not a bad thing. There'll be days where you want the larger #15, and there'll be days you want something that doesn't weight your pocket down as much. Just be warned that either one will be a gateway drug knife, and that not only will you be buying both, soon you'll be looking at stockmans, whittlers, wharncliffe trappers, and congresses. And then you'll discover custom made knives. Definitely spend some time in the Traditional forum. It's without a doubt the most pleasant, respectful, and giving knife subforum on BF or the entire internet. Browse though the hundreds of pages of the "What Traditional Knife are you Toten' Today" thread. Welcome to Bladeforums, and welcome to the addiction.
