Characters as classes can be seen in FF8.
Fallout Tactic classless system can be played as class system:
Combat role: Divide strictly into Small Guns, Big Guns, Energy Guns.
Support role: this divide into smaller subgroup, one really reserve for minor characters that usually get picked up from roster to do support things, then drop back into roster pool. Barter, Bet. And one reserve for a permanent spot in your team, like Doctor/First Aid, Sneak. They trade off their combat ability (and combat kill xp) for class skill xp (heal xp, pick lock xp etc...)
This one rely on a huge roster of personel or it cant be done at all. The necessity to play it like that is due to long game with different waves of enemies
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Anyway, which system work best depend on how you design your game. FTBOS is the very example of forcing a classless system work like classes.
In a counter example: Morrowind system is classes as you practice. BUt the shenannigans related to leveling make it feel more like a classless system rather than class system... Or is it vice versa? The leveling scheme clash much with the class/race/profession.
Mmm...oh yeah, very good point about Fallout Tactics. That reminded me I made my own classes back in the day. Each with their own perk and skill sets so I could try different combinations and then worked out which characters would get each build. Below is an exhaustive list - most were geared to a particular set of perks and allowed different combinations of races and anticipated the option of using perks that changed their evolution like Tag, 'Mutate', Gain (Statistic), but not the Bend the Rules and Break the Rules perks:
Leader & Explorer - Outdoorsman skill and for your main character.
Road Warrior - Driver based build
Master Trader - Barter build
Mr. Fixit - Repair build
Doctor Natural - High luck and assumed they had the base stats to get 'Healer' Perk
Doctor Lucky - Assumed they had to take the Gain (Statistic) Luck perk to get 'Healer'
Thief Demolition Ghost - Focus on Traps
Thief All-Rounder - Focus on getting Pickpocket perk
Sniper - Long range specialist
Bonus Rate of Fire - Long range specialist with Action Boy
Sharpshooter- Long range specialist with high perception but unable to make Sniper or Bonus Rate of Fire
Critical Bonus Ranged Damage - High Luck and all about max damage
Big Gun Psychotic - Super Mutant Big Gun build
Big Gun Strong Back - Human Big Gun build
Grunt Throwing Dodger - Naturally strong humans/ghouls with Small guns/Energy Weapons and throwing
Grunt Throwing Heave Ho - Lower strength Small guns/Energy Weapons and throwing builds
Grunt Throwing Cancerous Growth - Built really just for Harrold as his stats/skill set are odds and sods
Slayer Talon of Fear - Deathclaw Slayer build
Slayer HtH Evade - Human Slayer build
Silent Death - Stealth with focus on Silent Death
Unarmed Soak Hide of Scars - Melee Deathclaw HP soak build
Unarmed Chem Tough Hide- Melee Super Mutant HP soak build
Melee Soak Lucky Adrenaline - Melee Human HP soak build
Melee Pure Damage - Melee build with focus on base HtH Damage (but not slayer/silent death)