Like you I could never get my hummus to taste just like the store bought. It wasn't as creamy. I read an article, which naturally I can't find right now, that talked about processing the tahini longer. Since I've done that it's pretty darn close to store bought.
Use whatever recipe you have but put your tahini in the food processor first and process it alone for several minutes. Then as you add the other ingredients process them longer. It takes more than just putting them in the food processor and grinding them up.
Hope this helps.