I only like Scorn Defeat. I'm not into all that arty avantgarde shit, give me Sabbat any time of the day, who are about my favorite band of all time.
That said, I don't think both Sabbat and Sigh can be classified as black metal. Sigh is more avantgarde stuff, while I'd say Sabbat lean heavily towards oldschool speed/thrash metal and NWOBHM bands.