I would say that my first steps toward becoming someone who played rpgs were when I was pretty young. I didn't know that things such as rpgs were out there, but I vaguely remember using a deck of cards to play some sort of game I invented which included a castle, monsters, and nights. I don't remember much, but I remember that certain cards meant different things, and the color of the card was important as well. IIRC, I would have been in early elementary school around this time.
As I got older, I became an avid reading of fantasy and mythology. I was a huge fan of choose-your-own-adventure books. I also did a little bit of freeform roleplaying via AOL chat rooms. I had knowledge of the D&D name due to reading the Dragonlance books, but I really had no concept of what it was.
I had a very very brief experience with D&D 2nd Edition; not enough to really remember anything, but it was enough to expose me to the realization that other people were out there who enjoy the activities I did. (I grew up in a small rural community.) As a result of the "D&D = Satan Worship" phase, the game was pulled off the shelves of Toys'R'Us before I had a chance to get more into the game.
I then fast forward to 3rd Edition where I was surprised to find that a local gaming shop had opened and that they had D&D. I bought the 3.0 books, but didn't have much of a chance to use them before being shipped out with the military. During my first tour overseas, I was introduced to Rifts. I loved the fluff of Rifts, but I did not always love the mechanics of Rifts. The game was not hard to learn, it just had a few mechanical quirks which could at times create unbalancing results... especially with me being a new player and playing with people who knew the rules far better than I did. Somewhere along the line I also bought a GURPS 3E book, but I have no idea why or when; I found it when going through some of my old stuff a few days ago.
Returning to the states for a little while, I found that D&D 3.0 was now D&D 3.5 and the local gaming store had flourished and was doing well. I actually found a group to game with for a little while. I highly enjoyed D&D. There were a few house rules which the group I gamed with used that I didn't particularly like, but, overall, I was glad to play. The game had some issues, but not as many as Rifts. After a brief stint home, I was again shipped away.
A few tours later, I returned home to play D&D 3.5 again until it died and was replaced by Pathfinder and D&D 4th Edition. My group was unsure about switching to 4th Edition, but I used some preview material I had obtained from helping out at the local gaming store's preview event to convince them (at the time, I thought I would love it) and the group switched. At first I very highly enjoyed 4th Edition, but I seemed to get burnt out very quickly. It was fun, but, for some reason, I didn't feel like I was getting the experience I wanted, so I went on a search for a different game; this would be the first time I was actively looking outside of D&D.
Eventually, I tried GURPS 4E. I loved everything about it. It had the level of depth I enjoy from D&D 3.5, but it also had the few elements of D&D 4th that I liked (lesser power curve between levels - there aren't levels in GURPS; better balance than D&D 3.5; etc,) and also had merits of its own that I wanted (combat & noncombat being given equal treatment; increased realism; etc.) Perhaps what I enjoyed the most was the ability to build what I wanted; I found that I could even take those old Rifts books I have and convert the fluff I loved into mechanics I enjoyed. Likewise, I could do that with the D&D books I have.
Honestly, as silly as it may sound, I was at first afraid to show GURPS to the group I normally game with. I was afraid because there was so much negativity on websites like this one and over at the WoTC boards about how complicated the game was and various other things. I didn't find the game to be overly complicated at all, but the negativity still made me nervous about trying to actually run a game for my friends. Though, one day, one of my friends asked me what book I was reading, and this prompted the first group trial of GURPS. It went exceptionally well, and the group now trades back and forth between the two games.
One of the guys DMs D&D 4th Edition when it is his turn; one of the others runs GURPS 4E when he has a chance. As for me, I feel like I can't run a D&D game anymore. I recently tried; got to paragon level with the group, and they asked if they could covert their characters to GURPS for the rest of the story. I assume that means I've done well with the system when I run it. I was extremely surprised, but, it's ok with me because I've been enjoying the system ever since that first day with it. Anywho, that's my story.