While planetary sci-fi isn't exactly my forte (I lean toward post-apocalyptic and science-fantasy for any sci-fi), here are some ideas. Most of these are based off Star Wars d20 and its playable classes.
The Fringer
Known to survive on backwater or under-developed planets. Could have skills that relate to fighting a planet's natural threats. I can see them being an Evasion-based tank, and having resistance toward ailments like Poison and Blind (implants, immunities, etc), or having a high AGI and perhaps HP. Probably leans toward melee weapons, civilian-level firearms (weaker energy pistols, or reliable slugthrowers based on revolvers / hunting rifles / shotguns), and light armor to medium armor. Non-combat skills could involve foraging for healing supply ingredients, actually making those supplies from a crafting station or from a menu option, and being perceptive to out-of-battle threats?
The Noble
While not useful as a planetary survivor or even a fighter, their social skills and leadership know no bounds. Could have skills to add buffs or remove mental ailments/debuffs from allies, would open up dialogue choices in social situations if active on the team. Maybe has average stats across the board, as gimmicky characters who are useless in a fight suck. Equips could involve civvy firearms, maybe dueling melee weapons, and light armor.
The Sapper
Militaristic and based around technology and how to thwart it. I can see them having skills that allow them to fight robots / androids / cyborgs / power armor users more effectively. They might even be able to blow the enemy away with military-funded explosives, either as vicious single-target grenades or bunker-busting bombs (AoE or "true" damage that ignores defenses).
In non-combat scenarios they serve as a Thief or Rogue in fantasy tabletop RPGs, able to detect and disarm traps and breach locked doors (likely with explosive charges instead of lockpicking). Might be slow to act (low AGI), but with heavy DEF; their earthy wit and cussedness could give them decent MDF. Their loadouts for gear should include military-level guns (energy rifles, assault slugthrowers and shotguns come to mind), improvised and heavy melee weapons based off tools (engineer wrenches, sledgehammers) and medium-to-heavy armor.
The Cyberpunk
Not unlike a Fringer-Sapper combo for game stats, but based on digital technology and coming off as an anarchist punk (maybe one forced into service, or a stowaway on the crashed spacecraft). If the Sapper is meant to blow up or fry the circuits of robotic foes, the Cyberpunk should be able to apply ailments exclusive to them. Stuff like locking integrated weapons systems (akin to Silence), taking over the AI of robots (Confusion or Enticement, or a script-based effect to directly control their actions), messing with targeting systems (Blind), et cetera. Out of battle their skills are talented enough to hack even alien software, or simply override electronic locks.
For other combat skills the "punk" part of their name should apply, such as molotov cocktails or monofilament garrotes. If using cybernetics or implants as suggested for the Fringer, their "cyber" part can also come to mind. Maybe they can have access to more useful implants, or have more equip slots to use them at a time? They should be more dextrous than a Fringer but more wispy -- a passive Evasion and/or Critical boost, but less HP? Their weapons can vary depending on what they've filched as anarchists, and are up to taste. Civvy guns, melee weapons, stolen military weapons could be mix-and-matched as desired. I think their armor should be light, maybe light-to-medium. If power armor is gained later on, maybe they can find a means to hack it for their own use, despite not having heavy armor aptitude otherwise?
