i think when we talk about analogue or digital, as edo83 has said, it narrows down to drive and delay effects and tube/solid state amps...
if u use, lets say 3 drive pedals, a wah, compressor and a delay pedal, u can have the option of placing things in different order to get a wide array of sounds, apart from the knobs to tweak each pedla's settings. maybe that's one argument why some people prefer analogue over a single multi efxunit...
but lets say u have daniel sassoon's array of analogue pedals, and u turn half of them on, with all the modulation stuff on, well, it makes the overall sound sounds a little digital but not completely.. in this case, people may ask, whay spend a few $k just to get that kinda sound when i can just spend $600 to $800 to get a solid multi efx unit?
to each his/her own, but i think maybe the secret is to selectively combine digital and analogue together to get a great mix. most pros use analogue drives and compressors here and there, then it gets feed into a few digital racks for modulation effects, noise suppression, extra EQ'ing etc and then into a very solid tube or solid state amp... these racks are so darn high grade, i would think that they most probably would allow the analogue drive sounds be heard even after some modulation effects are applied...