Digital Interconnects - Which one is the BEST ??!!

Hello,

i am not initially wanting to hear a brand name but more a TYPE of connection.

is Optical better than Coaxial ?  Is USB better than BNC ?   What IS BNC anyways?!     I read somewhere that a COAX input that utilizes any old RCA cable is much worse than a dedicated COAX cable - that was news to me!

After i learn these things, i will look for a good brand, but if there is a TYPE that outperforms other TYPEs i want to begin with that...

thank you for your comments