The Kogan Agora is a budget level tablet, but for the money it's not bad. The big plus is that it runs Android Ice cream sandwich, and for a budget tablet the connectivity options are superb.
You'll need to understand that at this price point there will be shortcomings, and in this case the downside is the processor, its lack of power will mean that it's frustratingly slow. The battery life is also poor, and the display quality doesn't compete with the more expensive tablets.
That said, the Agora isn't bad value.
The jury is still out as far as the Polaroid M10 is concerned. Again it's a budget tablet, and such it isn't going to pose a threat to the better-specified (and higher priced) devices. The display quality will be average, and the performance slow - slower than the 7" version.
To be honest I would seriously recommend that you take a look at both the Kindle Fire HD and the Nexus 7. Both are extremely good performers, and very good value for the money. You may not find the smaller screen such a disadvantage when you weigh up the specifications.
If I had to make a choice it would be easy - I would go for the Nexus 7.