Worker placement is probably the most highly ranked mechanic on BGG. There are currently 5 games in the top 20, 9 games in the top 50, 13 in the top 100, and 23 in the top 200. I personally haven't played many worker placement games, but I am a fan of the mechanic. The detractor for me is that they often take awhile to play, and they are thinky games.
I'm only going to talk specifically about games I've played, since that's the only way to be honest about things. I will mention that I've heard a lot of good things about Stone Age and Alien Frontiers, and I want to play both of those, but since I haven't, I can't recommend them.
I had heard a lot of things about Agricola before I got a chance to play it. The biggest thing I knew going in was to make sure we played the family game before playing the full thing. The family game serves as an introduction and leaves a few of the variable cards out of the game. Agricola is all about running a farm. You need wood, brick, stone, etc. to build improvements, you need to gather animals and farm your land, and you always need to feed your family. All of these things take actions to gather the resources, and since everyone needs all of the same things, you have a lot of tension. I think Agricola is a well designed game, but it never really struck a chord with me. I can win my fair share of games, but there's just something lacking for me.
Lords of Waterdeep
I had a chance to play this at game night a few weeks ago, and I really enjoyed it. It's set in the Dungeons and Dragons universe, which I know basically nothing about, yet I still enjoyed the theme. You recruit agents: Clerics, Wizards, Thieves, etc. to help you accomplish quests. These quests earn you victory points and other rewards. Workers are used to recruit agents, build buildings (which gives everyone an additional spot to place their workers), gain new quests, and play Intrigue cards (which affect other player(s) in some way). The best part of this game was that it took a little more than an hour, and that was to teach 3 new players how to play and then play the game. It gave me a similar feel to Agricola while being more engaging and faster.
I talked a bit about Kingsburg in the Dice game article, but it warrants mention here as well. In Kingsburg, players use dice to influence advisors. The higher the advisor number, typically, the better things they give you. There are times when splitting up your dice is actually more beneficial, or even taking a lower valued advisor. What I appreciate about Kingsburg is that you almost always have options. You may not get exactly what you want, but the odds are that you'll be able to get something that helps you. Once you get the resources you need, you use them to buy a building. Each building gives you a different bonus. What really makes Kingsburg a game is the end of year combat. That forces players to spend time investing in their military instead of just playing a resource game.
Like I said in the open, these are heavy games, and with heavy games comes a heavy price tag. If you're really on a budget, this is a category to skip. If you're looking for a lighter game in the genre, go for Stone Age. Based on price and my enjoyment level, I'd choose Lords of Waterdeep. I think it has great replayability and has a good enjoyment/time ratio.