Company of Heroes and Homeworld are one of the few RTS games that make me deeply concerned about my troops on an emotional level...
Original War did a good job of this too, as you had VERY limited personnel - you couldn't just "train" 200 marines...You would have like 8-12 people who would change their jobs depending on what you wanted them to do, and if you lost one guy in combat, it would be a legit problem in several ways...Allow me to explain: A guy could collect resources to build a factory, then he can switch jobs into a mechanic inside of it to build a vehicle, which he can then drive - most vehicles had multiple spots for people (one for driver, one for gunner). Everyone was interchangeable, and throughout the game, your characters gained specialties depending on what you had them doing... This made it VERY hard to overcome losing a character. I mean he might be replaced at the start of the next scenario, but you wouldn't have the same stats as the previous guy, not to mention personality/chemistry kinda did matter too.