I've had a ton of Emersons, and more than a few Southern Grind Bad Monkeys, and a Spider Monkey. between the two brands you listed, it really depends on what you are wanting.
Southern grind has the best fit and finish between the two. you're pretty much stuck with a couple of variations on that pattern (tanto vs drop point) but they're both nice in hand.
as for the Emersons, if you don't mind the fit and finish not being perfect, and having rough machining in places, then they tend to be pretty solid knives against lateral blade stresses. They're very easy to disassemble and maintain if you tend to get your knives gross often... SG knives used to require a special spanner bit to disassemble, but that may have changed. While the Emerson is breaking in, you will run into lockstick, but if you have a tough thumb it's really not that bad.
Between the two, I found myself carrying my Emersons more than the SGs, but that's because I have a hard time beating on knives that are pretty, and I used to be rough on some of my knives when I was younger (at least the ones that advertised themselves as 'hard use').
Edge retention wise, they're both pretty similar. Both are very stainless, so I don't really believe it's worth getting too wrapped up between the Sandvik vs 154CM. SGs S35VN on the Spider Monkey seemed decent.
Durability wise, Emerson hands down. That's mainly because Emersons tends to use thicker blade geometry than SG. I tried several times to break my CQC7, CQC15, and Commanders prying out knots in wood, and prying up some cedar planks just to see what they could take. The blades bent over, but always returned themselves true when I let off the pressure... so they have excellent strength for tolerating nonsense. Never broke the tips off, but Im sure it can be done. Didnt try that with the Bad Monkey or Spider Monkey, but since they have thinner tips (better for piercing) my assumption is that they probably wouldn't have fared as well. Most sane people who enjoy knives don't do this to them though, so it may not matter to you.
For self defense, it depends on how you train. I don't recommend carrying a knife for self defense unless you actively train with it as such. The tip on the SG drop point has better piercing geo than their tanto... the tanto looks better in video, but it has a blunter profile to it, even with the sharpened top edge. If you care about piercing ability dont get the tanto IMO. I have limited instruction with knife fighting, so I'm not an expert. As a maker, if I was tasked with creating something for combat/martial arts I would make sure it at least had efficient geometry for thrusts. Other people may have different opinions.
In short, with the options you gave, if you want to beat on your knife go with an Emerson, if you want to have something that is still a good work knife that also looks more the part of its price point (no offense to Emerson, but you dont get bling for the buck from them unless you just want to admire their nice stonewashing) then get the Bad Monkey.
If you just want an Emerson Opener for fast deployment and value your fingers then Id go with a Spyderco Endura with Emerson opener to avoid the occasional slippage of liner locks I experienced from BOTH Emerson and Southern Grind's liner locks. YMMV. Hope this is helpful for you.