Assange maintained that he was fine in the UK, but worried about Sweden because it would be easier for the US to extradite from Sweden.
That's quite simply a load of bollocks. The UK has been pally with the US, was involved in Iraq with the US, and willing to extradite far more than Sweden in the past.
The UK doesn't even typically allow rendition flights to even refuel, and absolutely requires all extraditions to go through the strict legal process. I think it's mainly a pride thing about not rolling over and letting a former colony run amok extrajudicially in your homeland.
I can see why he didn't want to step on Swedish soil if he got a hint of US led shenanigans.
The main difference is that the UK judicial system is much more open than Sweden's, and he explicitly stated that he feared being held incommunicado in that country.
That's quite simply a load of bollocks. The UK has been pally with the US, was involved in Iraq with the US, and willing to extradite far more than Sweden in the past.