Nothing comes close to Loscil when it comes to ambient. It’s something unique. His music feels like manufactured emotions. Tim Hecker, Pan American, William Basinski, Christopher Bissonnette, Dead Texan, Stars of the Lid, and Biosphere come to mind, but they are not the same.
The thing I can recommend is some of the artists or albums that I also enjoy a lot. Radiohead, especially Amnesiac and Kid A. Kettel & Secede - When Can. Bohren & der Club of Gore - Sunset Mission, there’s an upcoming album of which they’ve released a track that sounds really good. You might like some of the early work of Eluvium, or maybe Max Richter. Those are more neo-classical ambient.
I do like Boards of Canada too. I like my music to be somewhat hypnotic, yet organic. I have been into extreme metal more than electronic lately, so I’m gonna leave an album here that was dropped this year of which I think it is amazing, just as amazing as Loscil has been to me for the last 13+ years. It is black metal, but not your regular black metal: Andavald - Undir skyggðarhaldi.
If you want to take that up a notch, check out Kaatayra. Or if you prefer extreme electronic, check out Xanopticon’s Liminal Space. I know this is way more extreme than Loscil, but on an emotional level, to me, they are as close as it can get.