Road Cycling - Stems

I have a Giant bike and the stem is the adjustable one. Im thinking about switching it out. Question is, what do I look for in a stem in terms of 'fit'? Ive read stuff about handlebars covering the front hub and clearance between elbows and handlebars. Whats the real thing to look for? The giant stem could give me an approximate size I guess but its really not equal in my opinion because certain positions I like the reach but not the height or vice versa. Any help?

Before buying a stem read the fit tutorials listed in my sig line. Some very good stuff there.

You can go through a bunch of these different sites on fitting, maybe get more confused or you can take the easy way out. If you have a good bike shop in your area take the bike to them. The can switch out different length and pitch stems until you find the right one for you. This might cost a little more than going through mail order shops but it will eliminate the indecision of purchasing the correct one for you.

Snowblower

The only test is experience. That stuff about obscuring the front hub may or may not work for you, but dont use it as a guide.
The "feel" you should be aiming for is a sense of relaxation in your shoulders, a bit of flex in your elbows, and a straight back at a comfortable angle. The exact angle is a personal choice but should vary between horizontal for all-out time trialling, to 45 degrees for relaxed touring.
Pick a good shop who will let you swap out stems. Use front-loading stems to make the process easier.

Set your stem where YOU like it. Where YOU feel comfortable. and try to find a stem that will give you that measurement.

There are too many formulas out there and they are just generic.

Of course if you want to be a pro rider the goal os to in time go the lowest possible, but I am sure you are not ou t for this so just be comfortable and enjoy riding.

Join up a few club rides or shop rides and keep your ear out for advice and listen.

On our shop rides here we help very much new riders with advice. Of course what they do with that advise is up to them. But advice coming from me and 2 other guys here is worth much more than what some business guy put up ona website.