At least with a home-built mac you know what is inside it ...
I've never bought a Windows ready PC nor built one myself but have instead succumbed to the over-priced crappily built machines that Apple produce.
My first machine a 2000 iMac (you know the coloured ones without the slot loading trays) was great for a while but suffered intense set backs from heat related issues. After using it for a few hours (in summer) it would freeze up and start throwing up random windows and eventually crash. My only way of getting it to start was to let it cool down (anywhere from 2-4 hours) and then start working again - not fun. To avoid these issues I used to have a little desk fan sitting directly above the machine which would have to be turned on all the time the machine was running - but if it wasn't on the right angle it would freeze up and cause said problems - all this because supposedly they could cool from convection - yeah right
My next machine was an eMac (2004 model) great machine but the DVD drive was retarded by apple engineers to not burn dual layer discs and faster media. It also has had a nasty habit of being completely picky about what discs it will accept - sometimes it will accept DVDs sometimes not - but it loves CDs - go figure. Another thing is it has had an annoying whining sound that shows itself about every hour or so which has been there from day one - not good for audio recording :(.
In line with this I also maintain around 90 macs for a college and have had interesting experiences with a wide range of different macs from iMac G5s (the first release with the dodgy capacitors - which Apple still won't replace - unless they're completely dead), PowerMac G5's with 19" Apple Monitors and less than stellar performance and stability from built in USB and firewire ports and the subtle yet annoying differences between the cheaper iBooks and more expensive PowerBooks.
I actually bought a G4 PowerBook after working on the quite well designed iBooks for a year - what I found was the USB ports didn't power portable USB drives (you would have to plug it in to two USB ports or power it from mains) the problem is that on PowerBooks the USB ports are on opposite sides of the machine - yeah smart design my arse. The other major issue was battery life - the iBooks would last for 4-6 hours while the PowerBooks only 2-3 - what a rip - especially since PowerBooks would be more likely used in the field for production etc. The other issue was heat - the PowerBooks get so hot that unless it's the middle of winter you would never have the machine on your lap due to the excessive heat they would give off.
Other issues I've found consistent with a lot of different macs old and new is the stability issues while trying to run two firewire devices off two separate ports. Alot of macs will either disconnect one of the devices or stop them both working until you restart the machine. This is completely unacceptable and a flaw that has been consistent through many models, Apple won't even admit that it is a problem - BAH!
All this combined with problems with the new 2007+ iMacs with the cheap TN screens that Apple is denying is a problem to the problems with the Nvidia chips in the MacBook Pros to god knows whatever else is happening inside their so called well built and designed machines.
Apple has persistently been able to hide these flaws by offering brand new, spectacular looking offerings to the masses every few months or so.
I need not go into problems with software nor the many other issues loyal mac users have had to endure - but I say this and I say this loud...
THE NEXT OS X SYSTEM I INSTALL (FOR PERSONAL USE) WILL BE ON A BOX I'VE BUILT MYSELF!
I don't care if it's a fugly hacked together piece of kit - it will work, if it breaks I will fix it, the only thing I will rely on Apple wise is their OS but hey if something better comes along then I'll go for it instead.
Apple has progressively become more belligerent towards its criticizers and tries to slap a NDA on anyone who comes even close to proving them wrong.
How long will people take this shit for?
I have long been a faithful Apple user and supporter but no more - they can literally suck my balls!