Find Most Expensive Queries Using DMV

SELECT TOP 10 SUBSTRING(qt.TEXT, (qs.statement_start_offset / 2) + 1, (
			(
				CASE qs.statement_end_offset
					WHEN - 1
						THEN DATALENGTH(qt.TEXT)
					ELSE qs.statement_end_offset
					END - qs.statement_start_offset
				) / 2
			) + 1)
	,qs.execution_count
	,qs.total_logical_reads
	,qs.last_logical_reads
	,qs.total_logical_writes
	,qs.last_logical_writes
	,qs.total_worker_time
	,qs.last_worker_time
	,qs.total_elapsed_time / 1000000 total_elapsed_time_in_S
	,qs.last_elapsed_time / 1000000 last_elapsed_time_in_S
	,qs.last_execution_time
	,qp.query_plan
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
ORDER BY qs.total_logical_reads DESC -- logical reads
	-- ORDER BY qs.total_logical_writes DESC -- logical writes
	-- ORDER BY qs.total_worker_time DESC -- CPU time

Reference: http://blog.sqlauthority.com/2010/05/14/sql-server-find-most-expensive-queries-using-dmv/