Fellow Mac user here, and I went through all of the same issues finding tools I could work with (except that I never really spent any time on LDD, as it was already surpassed by other programs by the time I became interested). Bricksmith was my editor of choice for a while, and I can say that it still works just fine for me under Mojave; I've not noticed any issues with running the program on my system. But Bricksmith is admittedly not a full-featured editor, and as noted, is no longer actively supported.
With the release of Studio, I found my interest renewed. The program allows for easy building with quick visual feedback, and is fairly powerful as far as what it can achieve. At the same time, there's really no way to work "under the hood" in Studio, meaning that if one of the program's features comes up short of what you want it to do, there's really no recourse but to submit a bug report or feature request and wait (hope) for their dev team to notice and act on it. (I'm looking at you, flexible parts engine…)
It also means that you can't get in and do any really precise manual tweaking or positioning of parts, so you have to work in a true LDraw editor for that. On Mac, that means Bricksmith (and it also means exporting from Studio's proprietary .io file format to .ldr and back again).
However, I'd also read about people being able to use LDCad under Wine, so I finally gave in and tried that—it worked! And it was not actually as tricky to set up as I thought: I found a very clear and concise online tutorial for setting up Wine, and as for LDCad itself, the only thing I had to do was install certain fonts used by the GUI. Other than that, the biggest hindrance is the difference in the physical interface between PCs and Macs (lack of a scroll wheel and—very notably—an Insert key), but that can be worked around. In short, getting LDCad up and running has really opened up the world of possibility for me as far as what LDraw can do—I no longer need Bricksmith at all, and I only go back into Studio for its fantastic photoreal rendering engine.
Oh, and I should add that LDCad is especially well supported by the outstanding help offered by the community here, both from the program's own developer, and other highly accomplished LDraw users.
With the release of Studio, I found my interest renewed. The program allows for easy building with quick visual feedback, and is fairly powerful as far as what it can achieve. At the same time, there's really no way to work "under the hood" in Studio, meaning that if one of the program's features comes up short of what you want it to do, there's really no recourse but to submit a bug report or feature request and wait (hope) for their dev team to notice and act on it. (I'm looking at you, flexible parts engine…)
It also means that you can't get in and do any really precise manual tweaking or positioning of parts, so you have to work in a true LDraw editor for that. On Mac, that means Bricksmith (and it also means exporting from Studio's proprietary .io file format to .ldr and back again).
However, I'd also read about people being able to use LDCad under Wine, so I finally gave in and tried that—it worked! And it was not actually as tricky to set up as I thought: I found a very clear and concise online tutorial for setting up Wine, and as for LDCad itself, the only thing I had to do was install certain fonts used by the GUI. Other than that, the biggest hindrance is the difference in the physical interface between PCs and Macs (lack of a scroll wheel and—very notably—an Insert key), but that can be worked around. In short, getting LDCad up and running has really opened up the world of possibility for me as far as what LDraw can do—I no longer need Bricksmith at all, and I only go back into Studio for its fantastic photoreal rendering engine.
Oh, and I should add that LDCad is especially well supported by the outstanding help offered by the community here, both from the program's own developer, and other highly accomplished LDraw users.