After lots of research and debate on what is "life-sized" I settled on a ballpark 36-42" hoof-to-top-of-head. After prototyping at that size, I was happy with the end 39". That's not to say other sizes are invalid, but that's my personal preference for "life-size." Anyways, here's my first plush: Twilight Sparkle. I'll be doing more in the future. Fluttershy is next on my list but, as you might imagine, it takes a while to save up enough for the materials. Doing a plush at this size with good minky is pricey.
I'll update when I make the next one. For now, here's Twilight.
Deviantart pages (with full-size photos):
Twilight Sparkle (first one)
Twilight Sparkle - Version 2 (Current)