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In your case, I would recommend an iMac and and iPad. Not sure what your budget is, but I think you would benefit from having a desktop at home to do most of your tasks, and an iPad to be portable and do some tasks on the go.

The iMac gives you the bigger, nicer screen and performance, and the iPad gives you the portability. I have a MacBook Air and an iPad (two iPads actually), but I also have a Thunderbolt display for when I need a bigger screen. I found the performance of the i7 2013 MBA to be excellent for the apps and games I run. Truth be told I don't NEED an MBA, as I don't take it out at all. When I am out and about, all I need is access to email, a browser, and maybe maps. The iPad rMini is PERFECT for that. When I get home, I could make do with an iMac, but I had already bough an MBA (I am a former Windows users and have a dozen PCs around the house, newest one being 5 years old), and I am running Parallels on my MBA so I can run Windows on it.

There is no "perfect" answer. Different combinations will give you similar results. But if you do not take your laptop out a lot and you dont need that flexibility, a desktop may be a better choice. What is your budget?

Yes, I thought that but my desk is front of a huge window. It's not a big issue in winter but in summer, sun is always in front of me, I my eyes get hurt from light and room gets too hot, so I need to go another room and I want to carry my computer. An iPad can do only half of things that I can do on a computer. iPad is perfect for doing simple tasks but it's not as powerfull as a Mac. This is why I will probably get a MacBook, but I am not sure yet.
 
I need to move my computer to another room. I rarely go outside with my computer. So I need something that is portable but I don't need something ultra-portable.

Like ZBoater said, why not an entry level iMac + 32GB iPad Air then. If you only need the capability of easily moving a computer from room to room the iMac accomplishes that purpose without the hefty laptop "tax," and also gets you a 23" screen vs a 15" which you find too small. It sounds like you wouldn't be happy w/ just an iPad, but that you could use one just to "dip your feet" into its capabilities.
 
Have you tried window blinds?

Yes, sun makes them hot and they heat up room again :(

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Like ZBoater said, why not an entry level iMac + 32GB iPad Air then. If you only need the capability of easily moving a computer from room to room the iMac accomplishes that purpose without the hefty laptop "tax," and also gets you a 23" screen vs a 15" which you find too small. It sounds like you wouldn't be happy w/ just an iPad, but that you could use one just to "dip your feet" into its capabilities.

I will consider it. I think I need time to decide which one, it takes too much time to make decision :)
 
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