no single favourite lens really. it depends on what i want to achieve and the setup that i'm using.
generally, i find 90mm to be a very comfortable focal length for APSC. i have a fantastic old elicar 90 for that and i use it quite often. for more modern lenses, i would warmly recommend the tamron 90 as a "cheap and good" macro lens.
different focal lengths gives different "feel" and needs different techniques to use effectively. handheld setups, i prefer shorter lenses (i.e. 50mm) so i can go close and to keep the overall setup light.
with monopod / tripod, i would use longer lenses like 100mm or 125mm and it affords me a more comfortable working distance so i don't spook the more skittish subjects.
generally, i'm indifferent :bsmilie: as long as its sharp and handles nicely with a long focus throw and a broad focusing ring, i'm fine.