Now there's a band I need to get into. What's a good starting point for someone who's into Vektor and Mental Vortex?
Long answer that doesn't really directly answer your question:
They don't really have any great albums for immediate access imo (Vektor and Coroner both have very nice hooks in addition to their complexity), but the first one most people would likely recommend you is The Music of Erich Zann. That one came from what I would call their first period, all their 80s material. You have to be able to tolerate kinda rough production and yelping Germanic speed metal vocals, but if you're OK with that, it's great tech-thrash. To me the follow-up The Principle of Doubt is stronger and has more interesting prog breaks, but a lot of people seem to criticize it even more harshly for production. The debut has some brilliant parts, but I'd definitely check it out last of the three.
https://www.youtube.com/watch?v=S_yEbZVqBWU
https://www.youtube.com/watch?v=eG9qPKqCdeA
In the 90s they increasingly moved away from thrash towards progressive metal, and saw the introduction of a new (and more able (but just as silly)) vocalist. Many people jizzm over their 20 minute Dances of Death suite, and if you just want something very different from most other metal of their time, its worth a shot. The following two albums (Kaleidoscope and Visions Fugitive) are the ones I'd recommend least, especially for a fan of tech-thrash, but the classical influences are pretty strong and interesting.
https://www.youtube.com/watch?v=E8OS1lUnhIo
https://www.youtube.com/watch?v=MV6Yr29kAqI
Then in the late 2000s they reunited, the first album of the period being pretty loyal to the style of their 80s thrash material, but more elaborate and with clearer production. It's maybe the closest they came to doing the same album twice, but the 20 year gap makes it still worthwhile. The following is almost "pure" progressive metal, introducing their first fully-competent singer and even a ballad, and is also their most cleanly produced, but despite containing maybe one and a half thrash songs, it's easily identifiable as them. I'd imagine it to be their most accessible, but probably not what a Vektor/Coroner fan is looking for. The newest just came out but right now I'd say it's very roughly between the last two, and while I love it so far, I don't think it's a good introduction to the band.
https://www.youtube.com/watch?v=Pxlmyb22dPQ
https://www.youtube.com/watch?v=dkyBH9qW0sA
Short answer:
The Music of Erich Zann and Lurking Fear, which are Mekong Delta in full tech-thrash mode and of their tech-thrash albums, apparently the most accessible/representative by consensus.
