Good advise from everyone so far. I'd say either a block plane or a #4 or #5 bench plane would be the best to start with. Whichever one you buy first, you'll likely get the other one as your second plane.
The most bang for your buck would be to pick up a good used plane. After WWII, small motorized tools became common in workshops, significantly reducing demand for hand tools such as planes. Manufacturers turned to keeping prices low to stay alive - in general, quality suffered significantly. I'd shoot for something made between the turn of the century and the middle of the century.
There are a lot of quality planes made during that time - some of my favorite bench planes are Stanley, Keen Kutter (single "K" models), Sargent, Millers Falls (lower digit numbers - ie: "9" not "90" or "900"), and Record (especially the "SS" planes with the 2 piece chip breaker). I'd make sure you could get one with a lateral adjustment on the frog. A great way to upgrade an old plane is with a new, thicker A2, O2, or high carbon cutting iron. I've done this, along with new thicker chip breakers and MAN what a difference! Hock, Veritas, and Lie Nielsen all make quality aftermarket cutting irons and chip breakers.
Used block planes - i'd go with the same makers listed above. I really like Millers Falls block planes - the fit and finish is better than their contemporaries. I like the screw type depth adjusters better than the wheel type adjusters (much more slop in the movement). I'd also go for one with an adjustable throat. These allow you to adjust the width of the slot in the sole of the plane, making it easier to control tear-out in some woods. Low angle or standard angle should suite you fine, though i reach for my low angle block more than my standard angle block.
If you're shopping new on a budget, i'd look at Stanley, Anant, and maybe Groz. They will all need some tuning to get the most out of them. I'd avoid the Buck Bros. junk available at the big box. I just spent some time tuning up a Buck Bros. jack plane (a #5) for a friend of mine. It's an absolute piece of trash - cheap materials, poor fit and finish, flimsey parts, bad ergonomics, etc. Don't waste your money.
Stanley's new block planes are actually nice quality tools. I've got a 12-220 (i think), and i really like the adjustment mechanisms - tight and responsive. It also has an adjustable throat and fits my hand nicely. If anything, i may pick up a thicker A2 cutting iron for it at some point. The stock blade takes an edge well enough, but my experience is that the A2 steel holds it longer.
For more dough, you can get a Veritas (
www.leevalley.com) or Lie Nielsen (
www.lie-nielsen.com). They're well crafted from quality materials. It's money well spent if you actually use the tool much, though my 1920's Record smoother cuts just as sweetly as my new, high end plane.
I've bought old planes on ebay with good luck. If that's what you're doing, do some homework first and avoid anything with broken, cracked, or missing parts. For some screen time research, i'd go to
www.supertool.com and click on "Patrick's Blood and Gore". I'd check out the #4, #5, #9, #9-1/2, #60, and #60-1/2. That should get you started.
Then, once you've got your old chunk of iron in hand, i recommend tearing into it - cleaning it up and tuning it.
www.rexmill.com will get you going. You might want a sharpening gage - the gray side clamping model works just fine and costs about $15. Woodcraft and Rockler sell them. You'll also want a flat sharpening stone or a piece of glass and some wet/dry sandpaper. Google "scary sharp method" for sharpening your blades with the glass & sandpaper method. I use a combination water stone, but the scary sharp method will get you started without spending much cash. Either way, if you don't have a way to sharpen your cutting irons accurately, you'll get very frustrated with your plane and won't get good results with it. Once you've got a good edge on the cutting iron, honing it only takes a minute or two.
I recommend a full tune up for two reasons.
1) it makes your tool work predictably and safely. If your plane isn't able to function properly, you'll get frustrated and set it aside, not really knowing its potential.
2) the process makes you very familiar with the tool, minimizing the intimidation of figuring out how to use the thing properly. Your skills will improve quicker if you fully understand the tool and how it's adjusted.
You don't need a cosmetic make-over. Chipped paint, a repaired cracked tote, or some surface rust on the lever cap don't effect how the tool works. I'd first focus on function. Then, if you want, you can get into gleaming display tools.
I started with an old Record SS #4 from an estate sale. Now i've got 3 #4's, a #5, a Veritas low angle smoother, a low angle and a standard angle block plane, a #78, a #2, a #7, a medium shoulder plane, a #140 skew angle block plane, a #112 scraper plane, and a handfull of card scrapers. I use them all regularly. In fact, i just picked up a fence for edge jointing as well. Start with a couple of the basics for general use. and the types of projects you do will guide your future acquisitions.
Have fun with it. I would not have imagined how much i use my planes when i brought home my first one.
Paul Hubbman