Performance Comparison of Queries...

Hi ,
I have table on which i have search records on differnent combinations.
Select Distinct ID from table1 where (C1 = 23 OR (C1=0 AND C3='Y') OR (C3=5 AND C5=9 AND C6=9))
So it is going for full table scan.
I have changed it to
Select ID from table1 where C1=23
Union
Select ID from table1 where C1=0 AND C3='Y'
Union
Select ID from table1 where (C3=5 AND C5=9 AND C6=9)
And I have created Indexes to support above.
1) Which Query will give me better results when Data in the tables are high ?
2) Which is better approach , if any other please give ur thoughts.
FYI, Second approach has increased the Scancount multiple times but there is not much diff in Logical Reads.
Regards,
Avnish Kumar