Please help me!?

okay, i have worn gles for 2 years and hate them so i am trying to do my research now before i get them in december! okay i have light-to-medium brown colored hair with dark brown eyes with kind of gold specks! the thing is is i was wondering i am going to get colored contacts.........probubly at walmart the brand i probubly going to be acuvue! so what is the difference between acuvue 2 colours opaque and acuvue 2 colours enhancers......also what colors do they come in and what color do you think i should get......i am leaning towards blue or green......what color do you think would look best, also i am white(not to be racist) with tanish but not to tan skin! also how long do they last and do you have to keep going and getting a new prescription everytime you need a new prescription?what color would look more realistic for me and would it compleatly cover-up my dark brown but not black eyes? also i am in athletics at my school and gles interfere with my sports so(continued below)