The ADODB is much more feature rich. It treats the XLS file as a database and allows SQL queries to be made.
It is also much more stable, and faster. The XLS file can be on a shared network drive where it is modified by a remote producer.
ADODB does not require Excel to be on the machine, whereas the Excel datalinq does require Excel to be running.
The ADODB is also more similar to how other competitor CG's have integrated with Excel doc's so it is more familiar to those users.
I always recommend ADODB over Excel.
#XPression