Are you targeting a specific region or country? Because the humans there can have a different preference than humans somewhere else.
<sarcasm>Also what is opposite of human...do dolphins prefer a specific format which I am unaware of?</sarcasm>
If you are referring the other end of the spectrum as computer-preferred-format then you are actually looking into the calculation of seconds since the UNIX epoch of 1970-01-01 00:00:00
Even though you might see something like
2014-05-02 08:41:52 coming from MySQL or
02-APR-14 08:41:52 AM from Oracle, the database is actually storing the integer
1399034512 because that many seconds have elapsed since the UNIX epoch.
The database has a setting to output a default format to the end user which is configurable so you could very well have something like
hh:mm:ss dd/yyyy/mm come from your database if you wanted to.
If you wanted to store
1950-01-01 00:00:00 then the database merely stores
-631134000 and formats it when you request to pull the data.
Now to answer your question:
In the U.S. you can expect the following format to go well:
I omitted the seconds because it causes too much noise
- 5/2/2014 8:51:32 AM <- way more processing power required of the
If you really want the seconds then you can show them upon hovering the item.
If you are worried about expanding/contracting widths then use a monospaced font such as COURIER.
One thing I highly recommend is displaying the date separate from the time like this in HTML:
<td style="width:20px;"> <!-- Spacer --></td>
<td style="text-align:right;">8:51 AM</td>