So here’s how I would personally divide up the bands you list into categories -
Lamb of God and Devil Driver are what I would regard as Groove Metal
In Flames, Soilwork, Dark Tranquillity and Amon Amarth are Melodic Death Metal (although of varying quality through their catalogues)
Megadeth I’d class as Thrash Metal…although that’s probably a little bit of a stretch.
Dream Theater are Progressive Metal although I’d probably just regard them as Progressive Rock.
I haven’t really listened to much melodic or groove based stuff for a while, am not a fan of Dream Theater and Mustaine’s voice grates on me. However…
If you want more groove in your metal try Machine Head, Meshuggah, Pantera, Gojira, Entombed and Ektomorf.
If you’re more into melodic death (not late In Flames or most of Soilwork’s output though) then give Eucharist, Miseration, The Few Against Many, Hypocrisy, The Black Dahlia Murder, Autumn Leaves, At The Gates, Intestine Baalism, In Mourning and Carcass a try. The list of listenable material here could go on endlessly…
Thrash I’m less of a fan…obviously you’ve probably already done Metallica and Slayer but you could also try Voivod, Kreator, Exodus, Testament, Municipal Waste and Vektor (I really recommend that last one).
Prog I don’t really listen to at all…the obvious recommendations based on everything so far would be Porcupine Tree, Steven Wilson’s solo stuff, Opeth (latter day, with earlier falling under Melodic Death), Periphery (although they’re djent really) and Protest the Hero.
Also based on the above also try Revocation, Dissection (you’re probably better off starting at Reinkaos and working backwards, which is the opposite of what I’d usually recommend but…) and massive outliers but two awesome albums - Circle Takes The Square’s release As the Roots Undo and A Wilhelm Scream’s Ruiner.
That should give you something to sink your teeth into for now. I could probably go on recommending you stuff indefinitely…