Wow, that was interesting, I have been away for a week and come back to this. Someone could have suggested building an AeroMax out of cardboard and got less comments.
I have a foot in both camps. I use a MacBookPro but dual boot it under Mac and Windows. Actually I find I use Windows 7 more than OS-X. I recently moved my good lady from a nice but old Dell Windows laptop to a shiny Apple MacBookAir 13 with OS-X. I also love the iPad and if you are only using email and browsing then it can do all of it with a Bluetooth keyboard/case. With all the helper apps it is a wonderful daily device.
You mention laptops that are large screen, Sony, higher spec. Current fashion is for small and light in many cases. Is there a reason you want a larger display, easier on the eyesight for a longer period ? I went for a MacBookPro15 rather than an Air13 to get the larger screen for heavy use. If you are looking at larger screens the new MacBookPro15 is excellent. The Retina Display is a very high cost upgrade which I would make certain you find useful enough before buying, interestingly the Retina version is actually physically smaller as well. For me it is not worth it and I would wait for the next generation when they take off the premium, it will be along with the next refresh.
Software
The first decision is are you ready to make the transition to Apple OS-X - my wife is not a geek and is finding it annoying. She made the transition to iPhone without a problem over two weeks and won't go back. She has not got to grip with all the swipes and is talking about going back to Win7. If all you do is browse and email Win7 is perfectly good. Interestingly if you use the Mac under Apple OS-X operating system the battery lasts usefully longer suggesting it is better optimised as you would expect for something designed by a single vendor.
If you can borrow a Mac and try it for a day or two then I would strongly advise that. Have someone walk you through the additional swipes and commands so that you get the value from them. Once learnt they allow you to get around the various programs you have open far faster but you need to learn them or it becomes confusing. It is a far more thoughtfully defined user experience and most software upgrades are included.
Hardware
The hardware is largely all Intel, the Mac is just Intel in a more thoughtfully designed form. i3, i5, i7 is about computing power, you do not need anything above i5 for most people. Clock speed difference between 2.0 and 2.5 Ghz in a laptop is almost impossible to see in daily use. The hard drive is well worth spending on. Instead of a 500Gb or 640Gb hard disc you do need an SSD as this can be felt for performance on every use. Do not pay for the upgrade to i7 if you buy the Mac.
Best case.
Order a MacBookAir13 or MacBookPro15 with 8Gb RAM and 256Gb SSD (now check the price!) to give you some future-proofing as it is not cheap and you cannot easily upgrade a MacBookAir. Use it with Apple OS-X and try and get used to the change over as far as possible. If it does not work you can literally just get a copy of Windows 7 and load it over the top of OS-X and have the most attractive Windows 7 laptop around. Do beware of Apple Fanboys seeing this and combusting ! Just say "I use bootcamp" and dismiss them 8^) it will work.
Sensible budget case.
Spec needs to be i5 or above, clock speed is not critical.
4Gb or more of RAM (PCs are usually easy to upgrade later)
Buy a model with an SSD not a hard disc. 120Gb or above.
If you know a friendly geek you can add one very cheaply and easily.
Now buy on keyboard, size, design, screen, warranty and price.
Apple has back end capability beyond a "Cloud" solution. iMatch for music across many devices. Backup, transfer, access across problems does give a FAR better recovery from theft or damage. Whilst many anti-virus vendors and MS etc offers cloud based storage it is not as well developed and integrated into the users experience.
I would also add that the difference between the instore Apple Genius desk and any other services I have had experience of from the Intel side of the game is massive. If you are not IT inclined this can be enough to change your opinion. Do buy it from a local AppleStore so you will benefit from their assistance in the long term. If you have a faulty iPad/iPhone and go to the Genius bar they provide the swap and transfer your data in two minutes. Service still counts.
If you have concerns about your data being in the cloud then just hand all your technology from the last 5 years back and pick up a pen. Too late. I would be inclined to trust Apple before many other vendors.
For me the Mac is a better machine for both hardware and OS-X software. If you make the effort to flip over then I believe you will enjoy it. It will aggravate you for a few weeks and try and keep someone around you to assist if you can. Then you will find it totally natural. If you are not so worried then don't stress Win7 is pretty damn good these days and the total outlay will be 50%.
