Question: I have a Canon 550D which I've been using for around a year now. I really love it and have learned a great deal with this and the 18 - 135mm kit lens. But now with experience I feel the need to get some better glass. I won't be buying a new body any time soon because I figure investing in some good glass is more important. 

As I have looked around, I see quite a few good used L lenses I can get in ebay for good bargain prices. But I know that the EF lenses don't have the same focal length in the cropped sensors. Is it a wise decision to buy these EF lenses or buy the cropped sensor alternatives?

I have the following lenses in mind that I am looking to buy down the line from the canon range over the next several months.

16-35mm f/2.8L, 24-70mm f/2.8L, 70-200 f/4L.

Are these apt choices for cropped sensors? I know most pros with FFs use these but I am a bit skeptic that they will serve the same purpose for me. If so what are the alternatives for this that have almost as good image quality?

Answer: 
The lineup of Canon crop (EF-S) lenses is not nearly as broad as the full-frame (EF) lenses.

* In the focal length of interest, some EF options give better image quality than the respective EF-S options.
* Additionally, some EF lenses offer features that are not available for EF-S lenses, such as weather sealing and stronger construction.
* (Not specific to the lenses you listed but) specialty lenses are only available in EF format, like fisheye and tilt-shift.

so yes, there are reasons to get full-frame lenses for a crop camera. For the specific lenses in question, @Joanne C's reasoning makes sense but today I personally think it is less important than it seemed to be in the past, as you have greater chances of upgrading your rebel to a higher crop body (7D class) than to a FF class. By the time you finally upgrade to FF class, you can sell your crop lenses for a good value.
As usual: it depends

* In terms of image quality, it's definitely wise as only the best part of the lens will be used (the center) by your camera. Lenses are usually sharper near the center and you will notice less vignetting.
* the downside is, EF lenses are usually more expensive than equivalent EF-S lenses.
* on the other hand, the EF-S 10-22 is a great lens, but there simply is no equivalent EF lens made by Canon. The 16-35 is simply a different focal range and the difference is very noticeable.
* your EF-S lenses will be useless when you upgrade to full frame
* note that you should ignore the famous "crop factor" in this regard. The focal length and field of view is the same for EF and EF-S lenses *on the same camera*.
* however, when reading a lens review that was made *on a FF camera*, note that the overall experience of that lens on a crop camera may be different (for example, I love the 70-200 on full frame, but rarely use it on my 7D as it gets "quite long" on that camera).

Simply said: When comparing an EF and an EF-S lens *of the same focal length*, the EF version will most probably have better image quality and cost more, but produce the same framing. Besides that, you need to evaluate other factors - for your lens choice - *not related to the EF/EFS mount type*, like focal length range, aperture, IS, build quality, size, weight, price and so on...