I'm not sure I've seen 12" length straight needles, mostly 10" and 14". I really dislike the 14" ones and never use them although I have a bunch of them. I like 10" okay. The 12" will be better than the 14" though. I find the 14" ones unwieldy and no fun to use. But... some people love them. I prefer to use circulars for most things, but like 10" fine for anything that the 10" will comfortably hold.
Keep in mind that for things where gauge really matters, the suggested needle size (how big around it is) is only a suggestion and may not be the needle you need to knit the given gauge even if you use the yarn suggested in the pattern. Everyone knits differently.