ODBC 5.1 to 5.3 - ANSI or Unicode?

[John Strano]

I have read the paragraph on choosing ANSI versus Unicode at...

https://dev.mysql.com/doc/connector-odbc/en/connector-odbc-installation.html

However, we've been using v5.1 of the ODBC connector and now need to move to v5.3.

Which do we choose; ANSI or Unicode?
There seems to have been no delineation let alone difference in v5.1, correct?

If so, which is more compatible with an extant DB that's had developers using v5.1 to connect? v5.3 ANSI or v5.3 Unicode?
Will both function without corrupting data read/written?
Can we choose either with impunity depending on whether we choose speed versus wide character set compatibility as cited at the URL above?

Thank you.