Just thought I'd post as I was in a very similar situation earlier this year.
I'd just bought the new retina MBP and realised I don't use my iPad all that often, if at all really. I only really noticed this when I would grab for the laptop rather than the iPad and from then I decided to sell it. Thankfully I sold it for a price which was more than reasonable for the 3rd gen, but it was in mint condition.
Over the last few weeks I've massively been pining for a tablet. Not a full-fat, retina'd up tablet. Just something which would allow me to not get crazy annoyed at using my iPhone for everything (mainly because the battery is god-awful)
So I took a plunge. I put the money I'd made into my wallet and headed down to the local store in my town and picked up the 16GB iPad Mini WIFI. My first impressions of the device where obviously how light it was, but then I saw the display, granted its not retina, but who cares? It fits my needs, I don't need someone to come and tell me how bad it is for them...I don't care about other peoples needs.
I ummmed and ahhhed about the Kindle Fire, Nexus or some real cheap eBay tablet as my needs are really simple, but I thought about all the money i'd spent on iPad specific apps etc. and realised it would be stupid to not continue within Apple's ecosystem. Yes its expensive to get into it, but for a product that holds its value as well as they do, why not?
tl;dr - Gone off on a tangent. If the iPad fits your needs even a little, its still the best thing on the market. For me, the retina version of the iPad was a little excessive as I never used it BUT the mini is perfect. Its light, holds it battery well and isn't all that flashy. It just does the simple jobs I need it to do without fuss. An Android run tablet wouldn't do it with such efficiency!
I think there is another reason why I don't get to pick up my ipad and use it as much, it is probably mainly because of my 12.5" Thinkpad. It is such a fast and portable laptop, yet much faster and beefier than most desktops, I believe that's what is keeping me from using ipad. Most of the time my laptop is within arms reach, and by putting it to sleep I can go through a full days work without having to plug it in. I think most people use their tablets and ipads as companion, while surely there are others relying %100 on it, but if I am watching a movie and I need to just look up something, (even though TV is HTPC) I just grab my thinkpad and look up stuff on it (it's truly always on, swipe of finger print). Maybe if I was not relying on my laptop to do my job I would probably accomplish all those things on ipad, may not even need the laptop like some people dropping their mbp/laptop completely, but the more I read I recognize the source.
As for replacing it with an android tab, I have this crazy paranoia about google and the apps downloaded from google, even if it is banking app, for some reason I happen to trust apple and their finance apps a tad bit more than google's.. Even though it's been fairly clear in recent reports that google protected user data a lot more than apple.. Still I use my ipad to deposit my checks, instead of my wife's android phone..