If you haven’t listened to Porcupine Tree, maybe try their penultimate album, Fear of a Blank Planet. It’s a modern prog masterpiece. Not exactly obscure, per se, but I feel Porcupine Tree have not achieved a legendary status like the bands you named above.
Also, give Opeth a try if you haven’t. Specifically Damnation and their latest 4 albums IF you do not like death metal. Most of their discography is of death metal/prog style, but the style of their previous 4 albums have been in style a love-letter to '70s prog rock. Again, probably not so obscure to those heavily invested in the modern progressive rock/metal movement, but they are worth mentioning. (If you don’t mind the death metal sound, their LP Blackwater Park is truly a masterpiece and I’d say easily one of the best albums of the past 20 years.)
Hopefully somebody else on here can give a more exhaustive answer. I, myself, am hoping to dive deeper into prog music, but I don’t know much outside of the few bands I listen to excessively (I.E., Porcupine Tree/Steven Wilson, Opeth, Devin Townsend, Gojira, Mastodon, Pink Floyd) and I do mean excessively.
