Which airport is better, 2nd gen express or 2nd gen extreme

Question

I use an older 2nd generation airport extreme on the 2nd floor of my house and needed another to cover another portion of the house and recently bought a 2nd gen airport express to extend it.
My question is, which is better(more powerful) to use as the main wifi hub: the 2nd generation extreme or the 2nd generation express?

Answer 1

The 2nd Gen AirPort Express is a simultaneous dual band product, which will produce both a 2.4 GHz and 5 GHz network. The 2nd Gen AirPort Extreme cannot do this. For what it is worth, the 2nd Gen Express is capable of higher wireless speeds than the 2nd Gen AirPort Extreme as well.
If you use the 2nd Gen Express as the "main" router, you will have the benefit of dual band performance for devices that connect to the AirPort Express in the main area.  If you have any 5 GHz capable devices, they will connect at higher speeds than other devices as well because of the dual band capability of the Express.
The 2nd Gen AirPort Extreme is not simultaneous dual band capable, so it will extend only one band from the AirPort Express, likely the 2.4 GHz band since it is the stronger signal.
It probably does not make much sense to use the 2nd Gen AirPort Extreme as the main router, since the Express will only be able to extend one band from the AirPort Extreme, since that is all that it can produce at one time.  On the other hand, if you are happy with the AirPort Extreme as the main router, and you are not looking for higher speed capability in the main area, you could continue to use the Extreme as your main router.  It does look more impressive.
As far as rated signal strength, you might be surprised to learn that Apple rates the smaller 2nd Gen Express as having just a bit higher signal output power than the 2nd Gen Extreme.
One question though....other than the modem, how many devices do you plan to connect using a wired Ethernet connection to your "main" router?