The first Mac I ever had access to - it wasn't exactly mine - was the family's Performa 450 (a.k.a. LC III). This was the computer that I spent hours writing HyperCard programs on. My first ever real hacking project was on a HyperCard stack that let you use drag and drop to assemble a pizza, then it would calculate how much the pizza should cost based on the toppings.
The 450 eventually got old and was replaced by a Performa 6400/180 in 1996. The 6400 and the 6360 were the first Performas to be built in a tower configuration. This was a pretty cool machine. It came with a 15" display with integrated speakers and had a subwoofer in the tower. To this day, I don't think I've owned a Mac that produced better sound out of the box.
The 6400 ran System 7.5, and it was my first machine with built-in networking (a 33.6k modem!). This machine was a bit odd in that some models had a Global Village hardware modem and some had a GeoPort software modem. It wasn't an option, no, it was just your luck whatever you found in the machine you bought. If I recall correctly, the tradeoff was between slow performance on the GeoPort and total system freezes thanks to the flaky driver software for the hardware modem. I had the misfortune to have the hardware modem and, three times out of four, the machine would freeze before MacPPP could establish the connection.
A couple of years later, the 6400 was getting a bit weak for the work I was doing at University at the time, so I was lucky to be able to upgrade to a Power Macintosh G3/266. I had the desktop "Outrigger" style machine, which was delightfully easy to work on at the time. Memory fails me a bit now, but I recall that this one had the luxury of an internal 100MB Zip Drive. I hacked the pants out of that machine. In particular, this was the machine that I first experimented with such dark arts as disk partitioning, dual boot and PowerPC Linux.
The next Mac I spent much time on was a PowerBook 1400cs/117 (the cs designated the cheaper passive-matrix display). It wasn't entirely mine, but I did get to borrow it for days spent studying in the University library. This machine had the famous "BookCover" outer lid: a section of the top case made of clear plastic that could be slid out and patterned paper inserts placed underneath. It also had such niceties as a built-in optical drive.
The next machine I had, after graduating was a Rev. A iBook G3 (Dual USB). I got this when I started my PhD and it was notable for such things as its whopping 10GB hard disk. It was, however, the first Mac on which I used WiFi. I remember buying the Airport Card for it at the Apple Store in Littleton, CO during a research conference there.
A year or so later, some money rolled in and I got a Power Macintosh G4/Dual-500MHz. What a great machine. In the years that followed, the G4 processor started to run out of steam somewhat, and this machine probably had the longest useful lifespan of any Mac I've ever used, in the sense that it remained performance-competitive with current machines for some time after it was discontinued.
The Mac that replaced the Dual-500 was a G4 800MHz "Quicksilver". This was the first machine I owned that had more RAM than I strictly needed - 4GB, if I recall correctly - and my first machine with a Superdrive. It doesn't live long in the memory. Apart from the proprietary Apple Display Connector, digital audio connectors and the crystal "baseball" speakers that also shipped with the iMac G4, it was otherwise a pretty unremarkable machine. I doubt if I ever actually used up the 5-pack of DVD blanks that I got with the machine. DVD writing has not been an important technology in my life.
A couple of years on, I got my first real job and bought a 17" PowerBook G4. What can you say about Lapzilla? What a great machine it was. Despite being Rev. A, it never gave me a day's trouble and I used it for three solid years. It only started to falter after I dropped it and bent the lower case. This mucked up the airflow in the case and caused the fans to continually run too high. Great machine.
I used Lapzilla until the first Intel Macs shipped, at which time the University bought 15" MacBook Pros for a colleague and I. Two cores in a laptop? Crazy talk! Apart from the odd swollen battery, those were pretty decent machines. I left the University not long after that to go part-indie-part-teacher and had to leave that Mac behind.
The 15" MacBook Pro was replaced by a black MacBook. The black was super-slick, but the original MacBook had the worst display I have ever seen Apple ship. The viewing angles were terrible and the colour shifts were horrendous. I was getting into serious photography at the time, and I was always really unhappy with the display. Apart from the colour, I never really liked this Mac and eventually gave it away.
Somewhere around this time, when I was under major deadline pressure and the MacBook had developed the dreaded sudden shutdown problem, I bought a 1.6GHz Core Solo Mac Mini. A neat little box which holds the distinction of being the only computer that I have ever totally broken (trying to replace the hard drive, I think).
After the black MacBook, the infamous Two Mac Experiment began. I acquired a 4x3GHz Mac Pro and a Core Duo 17" MacBook Pro. I've already written about all the pain that went with living across two Macs, but hardware-wise both of these machines were great. Loved them to bits. I still have the Mac Pro, although it's about to be sold, and I gave the MacBook Pro to my father-in-law last year to replace his iMac G3, just because I couldn't bear to watch him use that thing any more.
I replaced the MacBook Pro with a MacBook Air. I adore the MacBook Air. Yes, it's a bit spendy. Yes, it can't really truly cool itself that well and, yes, my first Air had to be repaired three times and eventually replaced, but you just can't beat the way it feels in your hands. Imagine two copies of National Geographic that can run Mac OS X. That's the MacBook Air. The Air also has the best glossy display I have ever set eyes on. It's glossy, rich and vibrant, but doesn't have the same reflectivity that the current unibody MacBook Pros do. Best Apple display ever.
After the aforelinked Two Mac Experiment died in a fireball of frustration and stress, I swapped it all for a unibody MacBook Pro 2.8GHz, which is my current and only Mac. I am really happy with this Mac and, in particular, the 500GB hard drive that I plopped into it on day one. Having this kind of performance and storage capacity in a nice, portable 15" package is really quite remarkable for this guy whose mobile computing experience started on a laptop with a 177MHz processor, an 800x600 display, 12MB RAM and a 750MB hard drive.