Each of these destinations have their own strengths over the other with London hosting the 2012 Olympic games later this year and Australia having sunny weather. I would recommend that you go to London since the Olympics are a bi-annual event.
I love the Olympics I'd love to see Michael phelps win at least 6 more medals that's once in a life time event we haven't seen any thing like that since mark spitz shattering many world records winning 7 gold medals in Munich in 72 don't forget Mexico 68 only 2 gold, well only two,one is hard enough and is considered one of the worlds most famous athletes. and he's an old man now well what 60s I think he could have gone on for many years but he quit competing early 20s because no endorsement deals like the multi million dollar contracts so he went to school and became a dentist although he is an a ambassador for the Olympics I'm not sure if he'll be there but I bet he will to see two of the best athletes WOW COOL I WOULD LOVE IT. but if not for the Olympics definitely Australia I'd love to see it and I love the accent much better.but I sure wouldn't like the flight from west coast N. America snooze fest bring ambien..
i have never visited either of the two but i would probably refer London because there are many places there that preserves contemporary arts and galleries that is centuries old now.just like the crowning glory of Trafalgar Square, London's National Gallery is a vast space, filled to the rafters with Western European paintings from the 13th to the 19th centuries. In this iconic art gallery you can find works by masters such as Van Gogh, da Vinci, Botticelli, Constable, Renoir, Titian and Stubbs. The world-famous British Museum exhibits the works of man from prehistoric to modern times from around the world. Highlights include the Rosetta Stone, the Parthenon sculptures, and the mummies in the Ancient Egypt collection. there are more beautiful places in the world you can visit to appreciate it's amazing ambiance. you can visit http://ivyjoybenitez.posterous.com/ to know more places that is uniquely beautiful :)
With the Olympics being in London this year in 2012 there has never been a better time to visit London. Lots of extra events crown jewels on show that have never been seen before at Buckingham Palace for the Queens Jubilee. If you want to get the most out of London a private tour might be good route with a registered blue badge guide. Check out www.dgatours.com as they tailor to suit your needs. Hope this helps