As with most of these threads it depends on your definition of "better". The A-7 could carry more ordinance than the F-18, could carry a very wide array of guided and unguided ordinance, had 6 wing stores stations, could carry more fuel for good loiter time and was excellent/stable in the dive- all good things for close air support.
On the negatives it was slow and single engine, so argubly more vulnerable, and by the time the F-18 matured into the C the A-7 was showing it's age airframe and avionics wise, and was not-multi role as the F/A-18.