'Holo' is a lot of fun to work with and can be made into a brandable in so many ways (Holotising for example) - but one thing to be careful with the term 'Holo'...
Virtually ANYthing with just 'Holo(+word)' WILL be subject to TM rights in the future and if anyone pays attention to Berkens' blog (The Domains), who regularly covers a lot of tm cases... it really does not matter which came first - the business or the registration. Good luck figuring out the logic there also as one never knows what will happen.
Microsoft could have easily just waited for their hololens product to be ready and slapped a UDRP on the domain owner and chances are - it would have been theirs... but for what they paid for it (i believe it was $6k?), it was just so much easier (and probably cheaper than the retainer fee's they pay) to just buy it for a reasonable number... less headache, less pub and probably less money.
Holographic+, Hologram+ and Holograph+ are mostly all generic and by nature will be safer to hold and gamble on, imo.
As far as best industry term... these seem to vary depending on what you're going after.
For me anyway, this seems to be more about what sounds best.. a rhythm, a flow..
... for example, what do you like better:
• Holographic Conferencing
• Hologram Conferencing
personally, i like Holographic Conferencing better out of these two. The biggest trade off it seems is the word Holographic has three more characters than Hologram
however... what do you like better here:
• Holographic Marketing
• Hologram Marketing
in this one, i like Hologram Marketing better. just a better flow and rhythm
These are all just my thoughts on the matter and how i have learned to perceive this all over the years... by all means, ignore everything i said if you don't agree.