The Best Tripod?

Well, there is no specific brand that is the best. Bogen/Manfrotto, Tiltall, Gitzo, Slik and even Velbon (and several other companies) all make good tripods. On the other hand, there are lots of bad tripods out there, and some of them are made by the aforementioned companies. These will have cheap friction latches on the legs that will eventually wear out, the part at the top where the legs join may be made of plastic, and many are unstable. A $25 tripod from Walmart is not going to be very good and you'll wind up replacing it soon. It isn't just Walmart either; every manufacturer makes both good and bad tripods. You can't just go by brand name.

This is what I look for in a tripod:

Legs:

The legs should be tubular and round in cross section, like pipes, not made of folded sheet metal. Round legs use collets (threaded rings) that screw down rather than latches. Latches are quicker, but they will wear out and/or break in comparatively short order. Collets are much more reliable, will never spring open unexpectedly if you bump them, and they will never wear out. The legs should also extend to a decent height, so you don't have to bend over too much to see through your viewfinder. Bear in mind that extending the center column will increase instabilty, so a tripod with short legs and a long center column is not going to be as good as one with long legs and a shorter center column.

Some legs are configurable, meaning they can be locked at different angles from one another. These can be particularly useful when shooting outdoors, in rough terrain, when you might have one leg propped against a tree, one in a hole and one on a rock or stump. The non-configurable legs are slightly more stable though and are better for flatter surfaces (and can still be adjusted independently to different lengths). This is one where you will have to use your best judgment.

Heavy or lightweight?

For studio photography, or if you are not going to have to carry it too far, the heavier the better. Use common sense here; a 400-pound steel studio tripod, mounted on casters, is not going to be a good idea if you are going to have to lift it. If you are going hiking in the mountains with it, even a 20-pound tripod isn't going to be a good idea. For this, you might want to look into a carbon fiber tripod, or one made with magnesium alloy, which are both lighter and stronger than aluminum.

Not sure what to call this, but the part at the top, where the legs join, should be made of metal, not plastic and it needs to be very sturdy. If you are doing studio photography, portraits or landscapes (and if you are using a pan head) it should have a bubble level built into it, so you can pan the camera and not have it look as if you are going uphill or down. This part comes under a lot of stress. Metal is less malleable than plastic and won't distort or break in situations where plastic will -- it is also less likely to become brittle in cold weather and it won't become soft and your tripod won't wind up looking like abstract art if you leave it in your car on a hot day.

Heads:

There are three main types of heads. these are the joystick head, the ball head, and the pan head. Joystick heads are not used as much anymore, and until recently, were usually found on older used tripods. They are not as stable as a ball head and so ball heads had pretty much supplanted them. However, they have recently started showing up again under the name "pistol grip head." They only will support about half the weight of a ball head, but in today's digital world of lightweight plastic and resin camera bodies, it might be becoming viable again. Just don't try putting a Speed Graphic and 500mm lens on one.

Anyway, the rule of thumb is that pan heads are better for landscapes and studio photography, where you can take your time setting up a shot. When you have to shoot quickly, a ball head is better. Pan heads are more precise but ball heads are quicker. Also make sure that, whichever kind you get, it can easily support your heaviest camera with your longest and heaviest lens. A fairly good rule of thumb is that if you are shooting something that doesn't move much, like posed portraits, landscapes, architecture and so on, you are probably going to be better off with a pan head. If whatever you are shooting is moving though, and you are going to have to shoot quickly, a ball head is probably better -- especially if your subject is moving fast or is moving erratically. Also, if you are using a pan head, the better ones have bubble levels built into them. The levels make panning and getting architectural lines straight much easier.

Adjustment knobs:

Short flat knobs apply more torque. However, they don't have as much surface contact with the threaded rods that they are molded around and are thus easier to strip and/or break. Cylindrical knobs don't apply as much torque, but will last longer. On a good tripod, it shouldn't take that much torque to lock it anyway.

Quick release shoes:

Make sure that whatever kind of tripod/head combination you get, you are not going to have a problem getting more quick release shoes for it. They are easily damaged or misplaced, and if you are using multiple cameras, it is much quicker to change cameras if they have shoes already installed on them. You don't want to miss a shot while you are unscrewing the shoe from one camera and installing it on another. As long as I am talking about shoes -- a rectangular or square shoe is okay, but hexagonal and octagonal shoes are a little more versatile, since they can be locked into more than one position. In any case, try to get at least two shoes, so you'll have one as a spare (sooner or later one WILL break or get misplaced).

Odds and ends:

Some tripods have the legs joined to the center column partway down by a jointed metal framework. This adds stability, and increases the weight-bearing ability of the tripod, but limits the possible configuration of the legs. Use your best judgement here, as this may or may not be a desirable feature. If you are shooting indoors, or on relatively smooth ground, this is more likely to be desirable, but it may cause problems when shooting outdoors, particularly in rough terrain. It is also often used on cheap tripods to make their flimsy legs a little more stable. Note that "more stable" is not at all the same thing as "stable."

Some tripods have retractable spikes that screw in and out of the ends of the legs. These can be desirable for outdoor photography, since they add stability on slick surfaces (like ice, mud, or the algae covered rocks in a river bed) but they are not going to do you much good when shooting indoors and can claw up your floors. This is another feature that you will have to decide whether you want or not.

Some tripods have one leg that detaches to make a monopod, and this may or may not be desirable, depending on what kind of photography you do. In my experience, this feature has only been handy in deep woods, when underbrush may not allow you to spread out a tripod, and when there is a handy tree to brace it against.

Some tripods have a reversable center column. This means that both the top and the bottom of the center column have threaded studs. You can attach a head to either end. If you take a lot of low-angle shots, this may be a desirable option. If not, it probably isn't -- but it won't hurt.

Ridiculous and unneeded bells and whistles:

This would include a hook on the bottom of the center column for adding weights, a carrying handle, and so on.