I need the smoothest and quietest auto focus lens for my Rebel T41. Canon EF-S 18-135mm f/3.5-5.6 IS Standard Zoom Lens STM sells for $439 new, $399 refurbished, and $369 used. Any advice on used or refurbished lens from you guys? I'm tempted to go with a used one. Sellers claim lens doesn't have any scratch, in excellent condition (on Amazon).