These are some of my favourite games out there, I don't remember what the first WP game I played was, but I can tell you I was instantly captivated by the mechanic. Playing a good worker placement game always reminds me of my love for RTS games on the PC and I can't get enough of how much planning and strategy is needed in (most) WP games. Check out some of my favourites:
Caylus: I like best for the amount of different routes to victory, so many options and lots of strategy.
Lords of Waterdeep: I like best for its fluid game play, easy accessibility and quick playing time.
Alien Frontiers: I like best for its unique game mechanics and its rich Retro/Sci-Fi Theme, Alien Frontiers also has a lot of player interaction with some of the tech cards and the area control mechanic of the Planet and its territories.
Space Station: A combination of space station construction as well as worker placement, you need housing for your crew and you need crew to make you money, victory points and fire your lasers. The worker placement is not super prominent in Space Station but it is still important and done in an interesting way.
Oddville Oddville combines city building and worker placement in an awesome way, and really mastering either mechanic can result in you coming out on top. Use your workers to gather resources and depending on where you construct in the city you will score more points.