In regards to the topic, Id have to say both have thier pros and cons. Generally emulation is much faster, but while its pretty accurate these days, its not "perfect" as some have said here. There's still a (admittedly smallish) percentage of heavily copper intensive software that doesnt work as intended. Also the "feel" is a bit wrong. Not really a flaw as such, but I also dont really like running hosted ontop of another OS, but that one is just personal taste. Mostly its pretty good, but any of the emulators that have custom chipset support have enough quirks for them not to be really for me. Personally I enjoy my combination of Amithlon plus my a1200/bppc/grex. Having said this though I can understand why people are happy with UAE variants, as for the most part theyre pretty good these days and I do still use Winuae from time to time.
Just my 2 cents :-)