HDMI Vs DVI & optical digital

Solution
For video they are equal.
For audio they aren't always equal.
Lossless audio such as Dolby TrueHD is only available via HDMI. SPDIF digital won't handle that much information. This means that on BD discs HDMI is better. On cable or over the air TV no difference.
HDMI is simply DVI+audio, LITERALLY. They invented the DVI first, then they figured, why not throw in audio in the same cable! and BAM! HDMI.

What's better? HDMI for no other reason than convenience, why use 2 cables when 1 cable does the job, plus I wager they haven't upgraded DVI so HDMI technology more advanced?

HDMI guy, is widely available, I dunno why you would do something else unless you have no choice.