Started out with M8 6x Leupold on my first inline, only problem close range it was a bit limiting. I have since used variable rifle scopes and never regretted that desicion. I have shot deer from 30 to 230 yards. I'd personally suggest a3x9/10 x40mm. Which one depends on what you have in the budget:
$200 range Nikon Monarch, Bushnell Elite, Burris FFII 3x9x40's
$300 Leupold VX II 3x9x40
$400 Zeiss Conquest 3x9x40