Android handsets, which this website is centered on, are multi-functional devices which can do so many things. The ability to access an app store is a big strength in what makes a smartphone great. I will tell you that due to the way the Android OS is distributed, there can be frustrations after you have bought your phone. Make sure you do research on the phone before you buy it, to make sure any buyer's remorse will be at a minimum. Apple makes 2 iPhone models that run on iOS. There are dozens of Android phones made by various manufacturers that Google has some, little, or no control over. Therefore, the experience you have from your handset can vary widely. Price is often a decent yardstick (at least in regards to Android phones) of how easy an experience you will have with a device and a company. The cheaper the phone, the more likely it is that there are lesser quality parts and less quality control during production. It may also be a good indication of the quality of customer service you can expect.
The iPhone will be very simple to use, because it was designed to be that way. I can't say much about Windows Mobile 7 as it hasn't been out for long and I haven't been giving it much attention, other than they are stressing simplified UIs as well.
What I can tell you is that the Android phone you are looking at is a knock-off of an HTC phone built by some Chinese company. I have heard enough bad stories about Chinese copies of popular phones that I will advise you strongly to stay away from buying one. If you can tell me where you live and what provider you have, I can make some safer recommendations.
Companies that I would have little problem recommending would be Motorola, Samsung, HTC, LG, Sony Ericsson, and possibly Huawei. However, even then, you cannot only trust the company's name. There are so many version of Android (1.5, 1.6, 2.1, 2.2) and so much different hardware that researching beforehand is necessary (at least in my opinion.)
So, where do we start?