How to describe a previous uncompleted PhD on postdoc applications?
I think this is a non-issue. When I review resumes from new PhDs (note: for non-university research positions, not post-docs), I rarely care about anything that happened prior to grad school. Any of these are likely to be fine. Still, my thoughts....

I think the most elegant way is to omit it completely.


Under education, you can list your completed degrees. As you say, anything impressive that you want to highlight from earlier years can be bullets here. 
Then under work experience, you start with the first position after leaving the unsuccessful PhD. 


That will take your work history back 8 years and give a reasonable explanation for what you did between undergrad and grad school. No need to account for every single year during that time. 

Your option #3 also seems reasonable, though I don't see the upside.


It is perfectly honest -- that was your title, and the technical staff will immediately see what happened (they shouldn't care)
Non-technical "resume screeners", who are more likely to be off-put by this, are less likely to pick up on it
But, this reduces your signal-to-noise ratio (you want your resume to pack a punch, not list irrelevant details), and you won't get many points for transparency. 


I see even less upside for option #1, though my analysis is basically the same as for #3. 

I would avoid option #2 -- it has the same upsides above, but could be seen as deliberately obfuscating (which is basically true) or trying to oversell.