While looking at some release notes for ACS v4.2 we stumbled across CSCsg62239. This bug blandly says "Binary text appears [randomly] in syslog output". Nice one.
In our experience CSV logging tends (with a few minor issues) to just work. ODBC logging slows the ACS to a crawl and syslog packets could go into a black hole and you'd never know.
If you have a legal or audit requirement to retain logs for any period of time - you need to use CSV based logs and collect/archive them regularly. This is where our csvsync client can help :)