In reply to Temp Lemming:
What sort of photography do you want it for? Walking e.g. landscapes? Does it need to be weather sealed?
My favourite lens is a 70mm macro which I also use for portraits (on a crop sensor) as it is the sharpest lens I own despite being a fifth of the price of a slightly longer f/2.8 zoom I used to favour.
But for walking I use an 18-55 f/3.5-5.0 "kit" zoom because it's weather sealed and is a lot cheaper to replace than my f/2.8 17-50 (a far nicer lens). If my 35mm prime was sealed I'd probably just take that as it's my second sharpest and faster - but I don't want to get water inside...
So in short, YMMV depending on what you want out of your lens.
Incidentally, if you want to take better photos, ignore the lens and get better light