Like any area of research, there is not complete consensus on whether using artificial sweeteners over sugar is good or bad.
Research done by dentists supports the use of sugar alternatives, particularly xylitol which is protective for teeth, because sugar directly causes cavities . As many of us know from neuroscience research done in the past decade, sugar also lights up the circuits in our brain associated with pleasure–with addiction. Our brain is hard-wired to see sugar as reward, which makes sense when you think about our ancestral history. Fruit that tasted sweet was fuel that could keep us alive. This parallel has been confirmed with sugars, but only recently have scientists started investigating no-calorie sweeteners effects on the brain. From early studies, it seems that calorie-free sweeteners create the same addictive loop in the brain as sugar. Despite the same addictive qualities, no-calorie sweeteners still have a slight, but significant, advantage for weight loss and weight management. 
When you delve deeper into the broader research, there are certainly concerning findings with almost any sweetener, other than stevia. In fact, stevia has been shown to actually provide health benefits. There is evidence that stevia is anti-inflammatory, anti-hypertensive, and anti-viral, among other benefits. 
All of the sweeteners you hear about–sucralose, aspartame, saccharin–are all chemically unique.  While certainly some of these sweeteners pose negative long-term health effects, I am doubtful that all will lead to cancer or metabolic disease. We have enough research to know that sugar is dangerous–it is high in calories, addictive, and inflammatory. We also have research that shows potential dangers in certain no-calorie sweeteners: microbiome disruption, addictive qualities, and increased cancer risk (in extremely high quantities).
So what is the take-away message?
Well, we are human. We like sweets. It is in our DNA, our brain to love the taste. The research has too few long-term studies with human subjects to base our choices solely on the existing science. Sure, if you feed rats one hundred times the typical intake of sucralose they will develop cancer–we know eating one food or chemical in excess is dangerous. In saying this, I don’t support sucralose consumption, but I am taking an objective eye to the facts.
I believe we should decrease sugar intake–we know the dangers there. How you choose to fill the gap with no-calorie sweeteners depends on your opinions and your body. If you like stevia, that is certainly the healthiest option according to science toady. If you want to drink your can of diet soda, go ahead. Just don’t drink 20 in one day! So what it comes down to is moderation. Find the balance that makes your body happy.
1: Sharma, V. K., Ingle, N. A., Kaur, N., Yadav, P., Ingle, E., & Charania, Z. (2015). Sugar Substitutes and Health: A Review. Journal of Advanced Oral Research/May-Aug, 6(2).
2: Murray, S., Tulloch, A., Criscitelli, K., & Avena, N. M. (2016). Recent studies of the effects of sugars on brain systems involved in energy balance and reward: Relevance to low calorie sweeteners. Physiology & behavior, 164, 504-508.
3: Saad, A., Khan, F., Hayee, A., & Nazir, M. S. (2014). A review on potential toxicity of artificial sweeteners vs safety of Stevia: a natural Bio-sweetener. J. Biol. Agri. Healtheare, 4(15), 137-147.
4: Roberts, A. (2016). The safety and regulatory process for low calorie sweeteners in the United States. Physiology & behavior, 164, 439-444.