I was a Mac user exclusively between about 1986 and 2001. At that point, I got a job that required me to learn to use a PC, and I eventually ditched the Mac for home use in 2002. This was due to frustration with the state of OS X at the time (I was staring at that spinning beachball a LOT), and secondarily for reasons of cost: the Mac I wanted cost roughly twice as much as a PC that could do the same thing, more or less.
I'm back to Mac only, as of day before yesterday. I've been using one at work for the past year or so (a MacBook, with Linux and WinXP running under VMWare), but my home computer was a rather nice, if aging, PC I built myself.
I had decided to switch back when I realized I'm better off giving up on gaming. The nice thing is that it suddenly removed lots of constraints on choice of machine, meaning I could get one that fits the rest of what I do to a T.
It's a 13-inch MacBook Pro. I jazzed it up with a Kingston 128 GB SSD and 4 gigs of RAM. Obviously, this isn't enough to store my photo library (currently weighing in at about 300 GB), but then I don't really want to keep the library on the workstation anyway, as long as I can access it easily. We already have a NAS for backups, so I simply decided to keep the library and any other files I don't want to lose there, plug another disk into it via USB, and switch on its autobackup feature.
(Why a MacBook Pro rather than a MacBook? Because I wanted one... and the price difference between the two really isn't all that big.)
I've never had as painless a setup experience as this. The disk and memory were incredibly easy to install, and everything "just worked." The only thing that hiccuped a bit was getting the system installation started -- it refused to boot from DVD the first time; I had to re-insert the DVD a few times and hold down the C key to get to the installer. Once up and running, everything went really, really smoothly: a totally different experience from the two-day slog of re-installing Vista on my old box after a hard disk crash.
The machine is by far the most responsive I've used. It boots up in about 15 seconds, wakes up from sleep as good as instantly, Chromium starts up as good as instantly, and even OpenOffice takes maybe ten seconds from click to cursor. It's not a slouch by the numbers, but it's far from a speed demon -- but in use, it just feels several times faster than anything else I've used. I figure this is due to Snow Leopard on the one hand, and the SSD on the other: my work MacBook is, technically, a hair faster (2.4 GHz Core Duo, as opposed to 2.26 GHz on the new one), but it sure doesn't feel that way. I'll probably upgrade it to Snow Leopard as well, somewhere along the line, although the SSD will probably have to wait.