Ronnin,
find a teacher, regardless of style, that you trust and connect with personally that teaches the complete art (ie, physical, energetics, meditative, academic, and martial aspects). the principles of tai chi are universal and although appear very different from style to style, at the core they are more similar than they appear.
Very true.
Please allow me to add
First there are 6 families now recognized by the PRC
Chen Style
http://www.answers.com/topic/chen-style-tai-chi-chuan
Yang Style
http://www.answers.com/topic/yang-style-tai-chi-chuan
Wu Style
http://www.answers.com/wu style Tai Chi Chuan
Hao Style
http://www.answers.com/topic/wu-hao-style-t-ai-chi-ch-uan
Sun Style
http://www.answers.com/topic/sun-style-t-ai-chi-ch-uan
Zhaobao
http://www.answers.com/topic/zhaobao-taijiquan
Tai chi is a martial art and a very good one if trained properly
The problems are first finding a good teacher and second (and this is a big issue) the student must be patient, it takes time.
And all Tai Chi schools are going to have an aspect of health it just comes with Tai Chi and that is a good thing.
If you train Wing Chun you can probably be able to defend yourself in about a year. You still have a lot to learn but you can use Wing Chun to defend yourself.
To understand Tai Chi, if you prescribe to what Tung Ying Chieh said (and I do), it takes about 3 years. But that 3 years is based on the old way of training, seeing your Sifu every day.
If you want the martial arts of Tai Chi it takes time and you must be patient.
You are likely to see more schools teaching Yang style Tai Chi for health than any other, but you are likely to see more alleged Yang style schools than any other. But if you find a good Yang school you will get martial arts. If they teach only Yang 24 and Tai Chi 48 form then likely you will not get martial arts, but it may not be a bad place to start. The first thing you need to look for in a Yang style school is whether or not it is traditional Yang and, as much as I would like to believe this is not an issue, what is the SifuÂ’s lineage.
If you find a Chen school it is more likely to teach you martial arts due to Chen postures being lower and harder to do at first. But I have seen some bad Chen schools
I cannot speak for wu or hao styles but my guess is they are about the same as Chen. There are just fewer schools for these styles and you are more likely to find the real deal.
Sun style hard to find but to the best of my knowledge it most Sun schools teach martial arts
Zhaobao, if you can find a Zhaobao school it will very likely be teaching martial arts.
Another style not listed is Yang style as it comes from Cheng Manching. If you find a school that teaches this style and the Sifu is William CC Chen or one of his approved teachers then you also have a martial arts school. I do not know anything about any other students of Cheng Manching and their dedication to martial arts; I just know William CC Chen is a martial artist and a very good one.
Also the Yang style of the Dong/Tung family has been martial arts as well.
But with that said if you are looking for a quick fix then Tai Chi might not be for you, if you have the time and patients to dedicate to it Tai Chi is a great thing to learn.