The first style I learned was a Yang form based on this style:
http://williamccchen.com/
The second style (a Chen short form), I learned from a different school, and it was much more difficult (with obvious fah jing motions), but I liked it better. I didn't study it very long, and my brain doesn't want to help me remember it.
The key is not as much the style as it is finding a good teacher. A really good teacher can make even the simplest short form of Tai Chi totally exuberant and exhausting.
*exhausting - but it will give you energy too!
Edit to add:
For anyone concerned about learning all of the movements of Tai Chi (if your physical coordination is severely lacking), then perhaps chi kung (qigong) breathing meditation might suit you better. (But I can't state how much better I prefer Tai Chi if I only had the choice to do one or the other - many schools teach both).
For self-defense, I would recommend learning Chin Na (joint locking) along with Tai Chi. You can learn to use Tai Chi as a self defense art, but I think it takes a long time. Most training of Tai Chi starts with learning the movements/sequence and not much defense application, while Chin Na will immediately teach even the smallest, lightweight person how to make a large, heavy person submit.
PS - Sorry if I killed your thread.
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Aspie score: 161 of 200
Neurotypical (non-autistic) score: 38 of 200
Autistic/BAP -123 aloof, 124 rigid and 108 pragmatic
Autism Spectrum quotient: 41, Empathy Quotient: 19