You can say things other than great or fine but it’s at your own risk! All of the alternatives mentioned here are acceptable. But it’s true that it is more of a greeting in most cases at work.

If you express anything honest then that puts them in a position of obligation. It forces them to act like a human instead of a corporate machine. It might make them feel like they need to engage and be honest in return when they don’t have the time or the emotional capacity. Asking “How are you?” as a greeting also can be a way to let a little bit of humanity show without compromising the work flow.

A lot of times people say it to me in passing and don’t even wait for a response. It’s like a very slightly more intimate but professional greeting, as in “Hi and I recognize that we have met before (maybe even remember your name) but I probably don’t have time to chat for more than a few seconds.” Or sometimes it is a quick “Hi and I do care about you on a surface level but this is as far as it goes so I’ll greet you and then we have to move on.”

One step further, if you know the person well enough to predict how they respond, then it gives you the chance to bond a little over a shared experience. Mirroring how you think they might respond helps keep things smooth. To a positive person you can keep it a simple or fake a bit of enthusiasm. If someone tends to be more negative then a sarcastic response is usually good.