I'm not a great fan of "diets" per se, because I believe that our diet is simply what we eat, but for all those who like to have a specific plan to go by, here's an article that might help you decide what to try.
We all know that the Keto diet has become very popular and that this diet says we should limit carbs to approximately 20 grams/day (or thereabout, depending on the actual plan you go by). This plan may work for short-term weight loss, but few of us can actually stick with it for any length of time, nor is it really healthy for long term use, especially for those with some medical conditions.
According to the article the # 1 diet is the DASH (Dietary Approaches to Stop Hypertension), tied with the Mediterranean Diet. Both of these diets advocate eating more fruits and vegetables, as well as whole grains, fish, legumes, nuts and low-fat dairy foods. Both advocate low meat intake.
The DASH diet cuts back on saturated fat and salt, while the Mediterranean diet allows for a daily glass of red wine and advocates the intake of more fish .
The "flexitarian" diet is a combination of DASH and Mediterranean diets and might be easier for some to adhere to. It doesn't require the intake of as much fish.
According to the article, the best weight loss diet is Weight Watchers, which stresses over-all well being such as "me" time. It would seem that one would lose weight following the DASH and Mediterranean diets as well, since food intake would likely be lower and more healthful.
The best diet is what's healthy and will work for you. For best results, check with your doctor and a dietician who can take your health conditions (if any) and likes/dislikes into consideration before getting started on a new plan.