Are you looking for calorie-free or one that has added carbohydrates?
Are you looking for EAA or BCAA's?
What in particular do you want in your intra-workout beverage as far as ingredients go?
Most companies offer performance enhancers (Size for example from Ghost), but I would not classify that as an intra-workout because it is creatine, betaine, senactive, beta-alanine (beta-prime), astragin, and epi
Intracell 7 has more carbs and calories but lacks some of the performance enhancers you may find in Ghost.
So this is why it's crucial to know what you specifically want to help narrow down the options.
The best option is usually a custom build of a few things pending your preference.