The traditional. Exudes a level of formality and class. Perhaps a bit too formal, in the wrong crowd could even come off as stodgy! Second syllable is a soft consonant leading to weak impressions being left in the mouth.
The pithy king! Shows a complete disregard for formality; expresses an air that one cannot just stand around all day saying goodbyes. Could be interpreted as cur or a slight if delivered with the wrong tone; one possibility is to extend the pronunciation. A rude "bye" can quickly be turned into a sincere "byeeee" or perhaps a reconsidered "byeeeee?" leading all parties to reconsider parting at all and instead get a hotel room and fuck all afternoon. That would be pretty hot!
The perfect way to show distance from those you are parting with. To say "take care" is to show you are far, farther, as far as humanly possible from the recipient. When you want to erect the Grand Canyon of in-difference or the Great Wall of China of not caring you bring out the Mr. Darcy of parting words.
Upon utterance causes all present to return to a childlike state of wonder, immediately followed by an instantaneous wave of melancholy at our lost youth and the pent-up frustrations that adult life piles onto us forcing us to spend entire Sunday afternoons wishing we could be children again; so you go to a Toys 'r Us and look at the dolls and actioning figures thinking if you could just pick one and play make believe for a couple hours maybe you could escape for your troubles, except the toys are all plastic ugly trinkets, so detailed you wonder if kids have any room for imagination at all, and as you ponder this you realize how ridiculous you look and/or how much you resemble a potential pederast as compared to a cool aunt/uncle buying a present for their niece/nephew except you have no nieces/nephews so instead you go out to your car and refresh Facebook on your phone and look at photos from college when you were last happy and cry forever. Also worth considering "bye bye" can be, as my mother once said, a little faggy.
Supposedly this means both "hello" and "goodbye" in Hawaiian, but how the fuck is that supposed to work?
And here we arrive to the only way to say goodbye, which is to say nothing at all. The old Irish Exit, it turns out that saying nothing in fact says everything. Were you in a rush to leave? Or were you too heartbroken at parting that you could not bring yourself to say anything at all? You always gotta leave them wanting more.
And seriously, who has time for the long, drawn-out goodbyes we see in movies and TV shows? You spend precious minutes trying to figure out how to express that you might die as soon as you take a step outside the threshold of the door, minutes that could instead be spent living! Just get on the damn boat already Frodo!
To say "goodbye" is to leave your heart with the recipient and you need that sucker to pump blood. Will you see them again? Probably. And if not, that "goodbye" is going to weigh you down like a sack of bricks. Instead, just walk out and never look back. You will be that much stronger for it.