NW beats UA, but will soon cease to exist due to the takeover by DL, which has a really crappy program, especially for TATL travel. Their 3 tier award chart is a nightmare and travel to Europe starts at 60K miles. If you originiate in EU then they also pop you with a huge surcharge. There are also lots of junk fees, like partner award fees, which you frequently cannot avoid for many destinations in EU.

You are a day late and a dollar short to be able to enjoy NW. Rather than get sucked up into DL next year, it is better to go with UA.