My guess of the metagame units mostly focused on land maps would be:
-Flea, decloaker, intel, swarmer, shotwaster.
-Glaive, arguably the best raider.
-Duck, slow raider acting as semi-riot.
-Dagger, fast raider skirmisher. Best raider on amphibious maps. Also good against Glaives, Swifts and decent against Scorchers in interception and offence.
-Scythe, surprise attack if the enemy doesn't deploy Fleas.
-Venom, fast riot for map control. Good with other raiders. Can also stun enemy gunships.
-Scorcher, best flatmap raider.
-Ravager, best flatmap assault able to act as a raider.
-Halberd, blockade runner, shotwaster and assault raider.
-Rocko, light skirmisher against Ducks, Venoms and Halberds.
-Scalpel, mainline riot skirmisher.
-Placeholder, skirmisher, crowdcontrol and semi-antiheavy.
-Scallop, best base drop unit.
-Roach, mobile bomb.
-Eraser, area cloaker. Great combo with roach.
-Rapier, deathballing aircontrol skirmisher.
-Trident, supplemental AA and Rapier counter.
-Swift, air control, raider defense.
-Gremlin, surprise AA, cloaked scout.
-Vandal, cheap mobile AA.
-Copperhead, fast heavy AA with AoE. Especially good against gunship swarms.
-Thunderbird, mass disarm and shield-drain.
-Raven, bomber and artillerysniper.
-Hammer, light artillery.
-Firewalker, riot artillery and anti-skirmish.
-Impaler, long range defensesniper.
-Catapult, long range riot artillery.
-Infiltrator, cheap anti-heavy.
-Skuttle, anti-heavy against unscreened targets.
-Grizzly, heavy skirmisher/artillery and anti-heavy.
-Ultimatum, anti-heavy.
-Dante, riot strider.
-Detriment. Ultimate strider.
-Valkyrie, transporter, base dropper, bomb delivery system.
-Vulture, intel and confusing radar jamming.
-Freaker, fast all-terrain con able to slow enemy units in both defense and offense.
-Quill, fastest flatmap con and amphibious.
-Convict, defense pusher and frontline reclaimer.