Honestly, I personally like the Loulou more, and would buy the Loulou. Also this is the Saint Laurent forum, so people might be biased.
However, the Alma is definitely more classic, and the Loulou is more on par with the puffy pillow trend that has sprung up this year.
I think it depends on your personal style. If you have a more classic/chic style, I would get the Alma. And if you have an edgier style, I think the Loulou would look better.
I think the Alma looks weird worn with the strap at this size. The buckles are super close to each other, but I think the Loulou looks adorable. If you prefer top handle bags, I think Alma would be a good choice. If yo prefer shoulder, probably Loulou.