depends really on your riding style and budget.
If you like tooling around town, arm ripping acceleration, and tire smoke and wheelies.. I'd go -1 in the front (16T) and +2 in the back (43). If you are a larger fella (read as 220+)i'd go 16/44 or maybe even 16/45
If you want a little more torque and acceleration, but are on a fairly tight budget go with just a -1 in the front. The sprocket is usually about $25, and if you can't install it yourself a bike shop will probably charge about $30 to do it for you (just a guess, i've never paid a shop to work on my bike).
If you enjoy your top end, but want a touch more grunt down low go with a +1 aluminum rear sprocket. This will reduce rotating mass, slightly (less rotating mass = more hp) and it will give you just a touch of extra grunt down low. This will also leave the option to add a -1 front sprocket later, in case you change your mind.
there really isn't any way of knowing what gear will suit you best, until you try them. I've done everything from a 17/40, 17/41, 16/41, 16/40, 16/45, and 17/45. I've figured out that for my riding style, and racing the bike the 17/45 is the best gear combination for me. (stock in front, +4 in the back)
Resident Drag Racing Expert.
ZX-16 in 2010
8.64 at 158 on motor
8.28 at 173 on nitrous
Back to stock for 2011.
9.24 @ 148
185 hp pump gas
New beast sitting in the garage. 07 ZX14.. Just a bare frame... for now.