Hmm, I've only heard Dom & Roland's first album, and it never really holds my attention the whole way through. Some cool parts, but the tracks always seem like they are ready to burst or climax but just never do, so it's kind of disappointing and samey. I prefer Torque. Techsteppin' is indeed probably the first album of the techstep era, as it gave the sub-genre its name, but it's more chilled out and has a kind of smoked-out hip-hop vibe that Torque doesn't have (instead it's just total raw, dark, sci-fi, urban paranoia).
Definitely check out Prototype years. Out of all of this it has the most variety and the most sophisticated tracks. Some are very beautiful, like all the Grooverider tracks, some are brutal like the Ed Rush & Fierce track "Locust", which could have easily been on Torque, and some are a weird mix of both, like the Dillinja track.