If you don’t want to splurge, this J.Crew Tank will fit the bill. It's a popular choice, while not very costly. Another strong contender for your wardrobe is this H&M Tank. While the price of this item is competitive, it will surely attract a lot of attention. You might also want to consider this Asos Tank. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you can afford it, then you absolutely must check out this Dolce & Gabbana Tank. This piece seems costly, but it's top quality. While you're at it, also have a look at this Alexander Wang Tank. Yes, this item is expensive, but it does not mean it's not worth it. You can also check out this A.L.C. Tank. You won't regret the money spent!