IMHO performance-tuning tools are valuble only to the extent that the user is competent and understands what the tool is doing. The tool smoothes the way a little (or a lot), and perhaps saves some grunt work of looking up scripts; but, in the end, the tool is not doing the performance tunung - the DBA is.

So rather than going for fancy tools i would suggest use OEM, its good enough to let you know the troublesome queries. After all its you who is going to fix the queries.