Allergic Rhinitis: This condition is the most likely diagnosis given the symptoms of cough, sneezing, and watery eyes, which are classic presentations of an allergic reaction, often to airborne allergens like pollen, dust mites, or pet dander.

Common Cold: The symptoms could also be indicative of a viral upper respiratory tract infection, commonly known as the common cold, which often presents with cough, sneezing, and watery eyes due to viral infection.
Sinusitis: Inflammation of the sinuses can cause similar symptoms, including cough (especially if postnasal drip is present), sneezing, and watery eyes, either due to infection or allergy.
Influenza: Although more typically associated with fever and body aches, influenza can also present with respiratory symptoms like cough and sneezing, and in some cases, watery eyes.

Anaphylaxis: Although rare, anaphylaxis is a life-threatening allergic reaction that can initially present with symptoms similar to allergic rhinitis, including cough, sneezing, and watery eyes, but can rapidly progress to more severe symptoms like difficulty breathing, rapid heartbeat, and a fall in blood pressure.
Angioedema: This condition involves deep tissue swelling, which can affect the respiratory tract and cause severe swelling, potentially leading to airway obstruction. It can be associated with allergic reactions and presents a medical emergency.

Vasculitis: Certain types of vasculitis, like granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis), can affect the respiratory tract and present with a variety of symptoms including cough, sneezing, and eye involvement, though these are much less common.
Sarcoidosis: A condition characterized by the growth of granulomas (inflammatory cells) in various parts of the body, which can include the lungs and eyes, leading to a variety of symptoms including cough and eye issues.