It does not matter what language Alsace Lorraine speaks, it is currently a France territory and should remain that way. Germany should just deal with it, Alsace Lorraine belongs to France now, so Germany needs to stop complaining. So yes, France has more rights to Alsace Lorraine then Germany does.
Alsace is now French territory, history notwithstanding. To say it belongs to Germany is to say the West Bank and the Gaza strip have no right to be occupied by Israel, which many of course say, but in reality we know is not the case. France got it fair and square, and the Germans shouldn't be whining about it any further.
We're talking about historical right, which is rather difficult in case of Alsace. Culturally and geographically, I would definitely say German. But in history, Alsace has both belonged to Germany and to France.
It's more about what you consider to be more important. I can only explain a bit about its history:
From the early Middle Ages to the late 17th century, most of Alsace had been an integral part of the Holy Roman Empire. It had a same position as any other German state (even though Alsace wasn't just ONE state) and had nothing more to do with France than any other (German) region located at the Rhine. It certainly also had the biggest contact with these Rhine regions (rather than with France). The situation changed after the annexation of Alsace by the French king Louis XIV. Alsace started to be influenced by France. It still remained Germanic, but the administration had become French. It was an integral part of France and France also didn't care that it was culturally (maybe also still in trade) much closer to the German states. France also didn't give anything about different cultures within their country. That wasn't important. Until 1871, Alsace remained German. Because of the long period, France now had a pretty strong claim on the region. German nationalists didn't care. They were trying to unite every West Germanic state on mainland Europe and Alsace was no different from Bavaria, Saxony or Hannover. A big part of the population also felt more German than French. It remained German until WWI. Germany also ruled it during WWII. Since then, it has been French. Historically, you could both say German or French. I'm more in favour of the Germans and especially because of cultural and early historical right, rather than the history of the last few centuries.
The story of Lorraine is more or less the same. The southern part (bordering the other regions of Lorraine) of what is now called Moselle (part of Lorraine that belonged to Germany after 1871 and which you're probably calling Lorraine right now) is culturally French. The northern part is culturally German(ic). It has only been part of France since the late 18th century, but it was less connected to the Rhine regions than Alsace (even though it still kinda belonged to it). I think it's more connected to France in a cultural way (compared to Alsace), but less in the historical way (unless you want to call the Frankish Empire French).