Beta-alanine, a non-essential amino acid, research has shown to increase Carnosine concentration. Carnosine is an intra-muscular dipeptide that offsets muscle fatigue during high intensity workouts. If you're looking to increase endurance and Nitric oxide production (pumps), you need beta-alanine.
If you like the tingly or itchy feeling that comes with some pre-workouts, beta-alanine if the ingredient responsible for that feeling.