Basically this macro will attempt to put you in the fastest form possible in your given conditions or the feral combat form. If you are in combat, have a killable enemy targeted that isn't dead, or you are indoors and not swimming, then you will be put in cat form. Swimming gives aquatic form no matter where you are. If you can fly in the area then you will be put into swift flight form. If you are outdoors then you will be put in travel form. The macro will try and put the user in those forms in that order i.e. even if you can fly or you are swimming, combat will restrict you to cat form or swimming will keep you out of flight form and in aquatic form. Holding the Ctrl key before hitting this macro will put you in aquatic form or travel form if you are in combat and trying to run away.
If your main combat form is not cat form just put " Bear* Form; " between [harm,nodead] and [nooutdoors,noswimming] *replace with desired form. If you are resto just remove [combat][harm,nodead] and then in every set of brackets that doesn't use the Ctrl modifier add ",nocombat" i.e. [flyable,nocombat].
Also for added fun for those people that prefer human over worgen form or just want a human druid, add "/cast Two Forms" to the end of the macro and whenever you are out of combat and in a different form and hit the macro, you will become a human.
I'd recommend keybinding this to shift + space. very easy to reach and hit quickly. This will still work with the control modifier. Reminder targeting an attackable mob will make your combat form appear so accidentally clicking a mob and hitting this can easily be fixed by hitting escape and then the macro again to clear your target first. I am fairly certain that this is the only macro that covers every possible situation. I hope some druids read this and enjoy it.