I've heard conflicting advice.
One camp says that baking smells - REAL baking smells, like cookies fresh from the oven - make your house smell homey.
The other camp says that your house should be smell-neutral. You can't guarantee that the people looking at your home will agree with your ideas of what smells good. Personally, I fall into this camp. I can't stand any of the air fresheners/oils/candles. Right now I'm 10 weeks pg and the smell of coffee makes me gag (and I know other people who always hate the smell). Some people think lemon smells clean, some people think bleach smells clean, some people would rather not smell either. In addition to personal preferences, sometimes the presence of an obvious scent can make people suspicious - are you trying to cover some other odor? Pet stains? Mildew?
So honestly, I wouldn't do ANY scent. Worked fine for me when I sold my house a few years ago.
Whoever buys your home can put their own scent in it later.