It depends what kind of eyes you have. I am Asian so I am all for finding lashes that are natural for MY eyes...believe me, it's harder than you think
But I am a lash junkie, always looking for something even ~more natural.
Anyway, I used to like wearing Ardell 109s, but they were a little too long for my eye shape. However, I do think that they are very natural and pretty compared to other ones that are thicker.
Right now I am VERY fond of wearing Ardell lash accents - I have 301s, and they are absolutely perfect! I apply mascara and then these accents and it seriously looks so real. Use some DUO lash glue and it should stay put fall day, just as long as it's not raining outside, you're not sweating profusely, swimming, or going outside on an especially windy day
I have heard GREAT things about Shu Uemura's criss-cross lashes for a realistic yet luxurious look. I am DYING to try their smokey criss cross lashes. I heard they are very luxe and natural looking, but still ad lots of volume. Once I save up some money I'm definitely going to invest in some.
Like another user said above me, you can reuse them! I reuse them daily, although I clean them often and they have managed to retain their shape. Here's a tutorial on how to clean them that works pretty well!
http://www.youtube.com/watch?v=EIvwND0Sm90
HTH!