Hey Alex

...well you've set yourself up a torturous situation

...but it's always fun the browse the possibilities! I do have a couple of 43's, 3 SWAT Models.., and I fooled around with Richard's Proto-type of the Monarch at the Oregon Show in April., so maybe this will help??
Since you mentioned your next purcahse as an EDC piece, I (personally) would rule out the SWAT....simply bacause of the 5" blade. Obviously that's a prejudicial judgement on my part, but I think if it's "Urban Carry" you are talking about, 5" is a little bit much.
So if we're down to the 43 vs. the Monarch..., there are a couple of considerations. They are two very different knives..., not necessarily because of Wee-Hawk vs Collver Bowie, or the ATS-34 vs. 440C blade steel, but the Monarch is twice the weight (I could be off a hair on this). I think the 43 is 4.1 ounces, and I'm not gonna look it up right now

.., but the Monarch is a little over 8 ounces..., more in the traditon of the Classic Stainless Steel handled Balis from the glory days of BM.
I'm an old guy, so I really like the feel of the older SS handles vs. the Ti-Handles. I also think both knives would probably make you pretty happy, but if you really intend to carry and use it everyday I might lean towards the Monarch because it's going to have the largest diameter pins ever produced on a Balisong..., making it a pretty solid choice for strength. The edge-holding capabilites of the ATS-34 vs. the 440C on the 43 is no big "Whoop" to me, but maybe a consideration depending on how you use your knife?
There is also the obvious point that the 43 is already "out there"...and we know it's a darn good knife!! I think the Monarch will be a very good piece, but as mentioned I only handled a "Proto".
Just some thoughts.....see ya!
"Hunters seek what they [WANT]..., Seekers hunt what they [NEED]"