c99 is definitely the best. i had one growing and let me tell u it had thc literally withing 2 dyas of flipping the lights. and it stunk way before that. like lemons an pineapple but strong. very strong. easy strain to work with too. packs a kick too.
Just finished up a 12 strain grow. There are 2 strains I'm keeping for personal headstash: C99 and a Sour D cross (Sour Cream, it's Sour D x G13 Haze). So I'd pick C99 or the diesel.