here's a good blurb about hydrowave bearings. now while i've never seen someone sit 100 fans next to each other to compare lifespans of sleeve- and ball-bearing fans, the rules seem to be that sleeve-bearing fans are cheaper to make, quieter and live shorter lives than ball-bearing fans.
while i can't vouch for cheaper, of the 70 or so fans i have there are very few ball-bearing fans that exhibit less motor noise than the sleeve-bearing ones, an observation that pans out over at silentpcreview. so if you're not interested in quietude, i'd go with ball-bearings due to price, availability and lifespan. there are some ball-bearing models that don't have the usual orchestra of rattling, however this is not usual.
panaflo fans are an interesting case. the recent batches have been made in china and exhibit wildly varying quality in terms of motor noise, due to manufacturing oversight difficulties. just recently matsu****a merged with nmb to create a mega-fan-manufacturer making several hundred million fans a year. the panaflo spec was intently revised, and the new china-made panaflos ("m3" - matsu****a minebea motor) are apparently superior to all panaflos that came before, both in terms of per-sample variability and absolute performance.
here's an extensive thread about the m3 panaflos over at silentpcreview, with input from someone who's been distributing panaflo fans for many years as part of her thermal design work.
i just noticed when previewing that the forums don't let you write matsu5hita (5=s).