In my opinion, the Canon would be the better choice! One of the worst things about the A3000 is the Electronic Viewfinder. It is very low resolution (as is the main LCD display). This is cause big problems if you ever have to use manual focusing (and trust me, there will be situations where the auto focus will not "lock-on"). It is also frustrating.. because when previewing images.. you do not get a accurate idea of what you shot... and sometimes can't tell if you should have re-shot.... and will have some barely usable images due to that.
The A3000 is just barely better than a good point and shoot. Slightly better image quality... but the performance is not good. Using it in low light will be more difficult than either the Canon or Nikon equivalents (especially if manual focus is needed.
Only my opinion, and I have only used one for about ten minutes or so... trying to help a fellow camera club member improve their photography (they sold the camera after that session, btw... and bought Nikon... and their photography improved, lol!)
With cameras... you get what you pay for. Don't get sucked in by the 20.1 megapixels... MP's are nice to have... but you would be better off with lower MP, and a better quality body. If $400 is truly all you can afford... buy used. You get a lot more for a lot less. If you need help with that, let me know.
quote from DPReview: The a3000's standout feature in a way is its price. You simply can't find a 20.1MP APS-C sensor tucked inside of a DSLR-like body for $400 anywhere else. It covers all of the basics and adds a few nice touches like dual stereo microphones for an overall value that's hard to argue with - if you can overlook some serious shortcomings in components and build quality.
( a little background on me so you don't think I am blowing smoke. I started shooting in the mid 60's, shot professionally (my own studio) from around 1982 to 1989 - quit due to burn out), still shoot for fun (with an occasional paying job that I think will be fun). Also shoot underwater a good bit. Currently shooting a Nikon d800, with a lot of lenses and gear)