It depends what your priorities are.
If it is cost, rental costs are higher in Wettingen, but i think tax costs are higher in Nussbaumen. So what you dont pay in rent, you pay in tax.
I like Wettingen because it is effectively a city- 2 swimming pools, 2 major shopping areas, all within walking/cycling distance. Oh! And fabulous gyms

Baden train station is equidistant to Wettingen train station, and has more options for the trains into Zurich, Bern, Basel- depending on where you plan to work/play.
The exit off the motorway is more convenient for Wettingen than Nussbaumen.
Akido, football, ballet for the kids- many people from surrounding "villages" go to Wettingen for after school kids activities.
Depending on how long you plan to stay, all 3 "levels" of secondary school are in Wettingen. Are they in Nussbaumen? Anyone willing to sell the benefits of Nussbaumen, online at the moment?
Afterschool care for your boy- it of course depends on the school timetable, which is different every day of the week, in every school.
The creshes in Wettingen are full, and for other reasons (which will take another rant) wont take kindergarten or school-aged kids. You may be able to find a "Day mother"/tagesmutter.
Some school also have a care option for the lunch-time, as kids are expected to come home for lunch.
Try these websites:
http://kinderbetreuung.liliput.ch/ http://www.betreut.ch
Views are probably nicer in Nussbaumen, and it is probably a little more laid-back.
Ehrendingen is also an up and coming good place to live- but you need a bus to get up the hill from the train station from Baden.
Though the Niederwenningen train station is close too- within biking distance.
3 weekly washing is just silly(!!) find another flat!
once a week is normal(ish) and sometimes you can sneak some in if you get on well with the neighbours.
PS: any long-timers out there planning on getting into an argument with me about where the border is between Wettingen and Baden wrt swimming pools & secondary school - forget it... its pedantic(!)