Sucralose/splenda is gut poison and was a major contributor to my gut imbalances. Some studies in mice show that it can kill up to 50% of good bacteria. That was just mice though. Haven't seen any good studies with humans.
Xylitol( not really classified as artificial sweetner) can also cause some disturbances. Higher doses can cause cramping and diarrhea. Xylitol seems to affect the adherence and habitat of good flora. Sugar alcohols in general should be avoided.
Stevia is a safer sweetener but I did notice it to cause some cravings and blood insulin/sugar issues. Stevia seems to lower my blood Sugar causing some lethargy. Some might be more sensitive than others.