Everybody has a different preference. How long have you been knitting? If you've done a bit, what kind of size needle and what needles have you been using?
I would say buy whatever's cheapest until you know what kind you want. That will probably be plastic. If you find them too slippery, you may be a loose knitter, and are likely to prefer wooden or bamboo meedles.
If you find them too sticky/not slippery enough, you probably knit tightly, and are likely to find metal needles better.
But rather than fix your gauge quirks with changing needles, I recommend you focus on knitting more averagely - if you are a tight knitter, try to loosen up, etc. You will really be glad in the long run.
Then next time needles are on sale, buy your favourite size in both metal and bamboo/wood, knit a bit with each and see which you prefer.
P.S. I prefer metal/anything with a very pointy tip.