I'm just a 'murrican*, so I tend to use "aitch" pronunciation of the letter "H". In various videos I've noticed that some folks in the UK and Australia use the "haitch" pronunciation.
HDMI -- I say "aitch dee em eye" while I've heard some saying "hatich dee em eye"
Which do you use?

* FYI, I speak with a Californian accent - with certain aspects that would identify me as being from Central or Southern California. Of course there's another way you can tell that I live in Southern California -- ask me for driving directions -- I tend to put the definite article "the" before the freeway/highway number/name.