I've owned Apogees and MartinLogans and have heard many models from both manufacturers that I did not own. Two generalities I've drawn are: 1) Horizontally, ML has a narrower sweet spot, and 2) Vertically, the Apogee has less dispersion. The vertical dispersion on Apogees appears limited to height of the ribbon and has a "wet blanket" effect on the highs when your ears exceed the ribbon height. This shouldn't be a problem on any Apogee all-planar models with the exception of the Caliper and Stage which are each shorter than a standing person's ears. Because you asked about the "sweet spot", I guess the vertical aspect is not really on point, here. But, it was the only major limitation in the dispersion arena for the Apogees I've heard.
The ML's narrow sweet spot has not been an issue for me because usually when I listen critically, I listen alone. The sweet spot is wide enough for one person--but not much more! btw--I'm not commenting on the quality of the reproduction in this comparison, just the "sweet spot" size.
So, since you asked about planars with a wide sweet spot, I'd say the Apogees certainly better the MLs.
The ML's narrow sweet spot has not been an issue for me because usually when I listen critically, I listen alone. The sweet spot is wide enough for one person--but not much more! btw--I'm not commenting on the quality of the reproduction in this comparison, just the "sweet spot" size.
So, since you asked about planars with a wide sweet spot, I'd say the Apogees certainly better the MLs.