When I sell a computer people always ask me about battery life, RAM, speed as if those are the most important things. They are not.
The two most important characteristics on a computer are the screen (that's what you look at all day long) and the noise level (even a tiny whine or the occasional clickclick from a harddisk can be incredibly annoying and distracting - for that reason I cannot recommend fast 7200 rpm harddisks in a laptop).
The thing I like most about Macs is that most of them are quiet. I build/used/repaired hundreds of PCs, and sooner or later (bar a few exceptions) they always sound like a jet engine. It might not matter much in an office, but at home I find it unacceptable. I have a 17in MBP and a 24in iMac in my living room, and both are VERY quiet.
The iMacs have gone downhill in expandability over the last few years. Since 2009 you can't simply use any harddisk anymore, you need to use a harddisk with a build-in temperature sensor. Or use third-party software to regulate the harddisk fan. The new 2012 iMac is a nightmare to open up, and even the techs don't want to do it.
I would recommend a Mac Laptop: it is quiet, has a good screen, and you can take it with you. I use a 2010 17in MBP with a 2,53 GHz Core i5, 8 GB of RAM, 512 GB SSD (just upgraded from a 256 GB), 750 GB HD, external LightScribe DVD writer. I got a 2011 17in MBP with a Core i7 and 16 GB of RAM which is twice as fast but sold it again. I didn't need the power, and the fans run too often for my taste.Screen size:
a 13in is wonderful for portability, but you might find the screen estate a bit limiting. A good combination might be a 13in with a 24in monitor. Get an LED monitor, not an LCD (the energy savings can be substantial). A 17in is my preferred size (I've used one for the last 5 years) but its weight is noticeable. A 15in might be a happy medium for you. Retina is great but not widespread yet. New Retina models are expected in June (see http://buyersguide.macrumors.com/
), so if you can afford it you might want to wait.Speed:
I find a Core i5 is a good compromise between power and heat production. The i7 has more power, but the fans run distinctly more often. The i3 is not really worth it - you loose too much power for very little financial gain.Expandability:
The MacBook Pro is actually quite easy to get into and upgrade: I have and recommend 8 GB RAM, a 256 GB SSD and a 750 GB HD, with the optical drive in an external enclosure. The MacBook Air is great for portability but forget about expanding anything on it.Software:
I still run MacOS X 10.6.8 Snow Leopard - I don't particularly like Lion or Mountain Lion. The monotonous greyishness might be a designers dream, I find it bland. Snow Leo still has lush gorgeous colors as distinguishing features without drifting into the garish mickymousiness of Windows. Windows & Linux:
You can run a range of operating systems in emulation - I run Win98, Win2000, WinXP, Win 7, Ubuntu on my MBP (that's where the larger SSD comes in very handy, though 256 GB is plenty for this). VirtualBox is free but neither I nor a friend have made the best experiences with it (might have to do with the German keyboards and the English WinXP system, but it was exceedingly buggy and not worth the savings). I got both Parallels and VMware Fusion as part of $49 bundles, and they are much better. You can even run Snow Leo Server (available from Apple for about $25) in emulation (which you can't do with the normal Snow Leo).Backup:
The importance of at least one backup can't be stressed enough. Better have two, one of them off-site. A theft, a burglary, a fire will still be a nightmare, but it will only cost you money to replace the computer to be up and running again. My father has over 84,000 pictures in his iPhoto library - if they should be lost I better not come home again.
What I like especially about the Mac is how well it works: currently I have FireFox (3 windows with 14 tabs) and Safari running (36 windows with 156 tabs), Word, Excel, Entourage, NaviCat for SQlite, REAL.studio, Xojo, EverNote, Win7 in VMware, Preview, GraphikConverter and about 15 smaller apps (I highly recommend Alfred
to everyone). My Mac has now been running for over two weeks like this (since the last system update required a restart). I try this on any of my Windows machines at work they go pear-shaped. Windows machines scroll a lot faster but that is a sham because Microsoft didn't put a max scroll speed in, which means they can scroll so fast to be useless.
If you buy a Mac be prepared for some adjustments - some will be easy, others will be hard. I accompanied about 40 people from Windows to Mac, and most moan for 4-8 weeks "maybe I should stay with Windows". The biggest hurdle seems to be to get rid of the complicated way of thinking that Windows seems to instill. However except for one (a hard core gamer who should never have bought a Mac in the first place) nobody wants to use Windows again.
There would be lots more to tell but duties await.