All three are excellent foreground plants. I have one tank with dwarf hairgrass and another with microsword as a carpet and HC covering driftwood. It really all depends on the look you're going for. Depending on how you want your plants to contrast, each can be used.
I prefer dwarf hairgrass if the tank size is relatively large enough for the height of the hairgrass. HC is great for a lush foreground but can be disturbed by fish and may be hard to keep planted depending on the substrate. Microsword just looks too messy in my opinion.
Be aware that once you introduce moss into a tank, it's hard to get out. Little pieces will find their way all over the tank and start growing. Moss can get very intertangled into your foreground plants making them look unattractive and/or become a maintenance nightmare. This is especially uncool if you decide to sell some...
All 3 are way cool plants though. Just pick one and go with it. Try them all over time.