Warlords: Battlecry series has 4 different resources and a ton of different factions. The last in the series had 16.
You create a hero unit through a race/class system, and then you can customize it through a full stats/spellbook/skill tree/equipment system. The level of depth in customizing your hero is almost on par with most action/adventure rpg games. No, it does not play like one. It plays like a pure RTS. Your hero is treated just like a normal unit in-game... just a really awesome and important one.
Then all of the units in the game also level up, though their progression is strictly linear. There is no customization. Though every faction does have "general" units, who are really advanced and typically get a spell or two as they level up.
Your hero also has a retinue, so you can save leveled up or special units and take them from battle to battle. There are even ways in the campaign to get super-special units, such as dragons, or units not normally available to your faction. If units in your retinue die, they die forever. You can also set your hero to have perma-death, and they grant him a x2 xp boost if you do so.
Grind isn't necessary for online play, as the set-up screen has an impressive array of options for customizing gameplay, including giving people the option to create a hero of a certain level from scratch just for that game.
Unfortunately, it's never been a series with a huge following, probably because it's never sported super flashy graphics or obnoxious art direction, blistering pace of gameplay, or a harshly unforgiving rage inducing learning curve (which seems to be what draws competitive gamers). It's been my favorite RTS for a long time.