Choosing battery replacement for non-retina MacBook Pro Is there any objective comparison of third-party batteries for non-retina MacBook Pro (eg mid-2010)? Alternatively, what are the possible strategies to choose which manufacturer to buy from?

Apple officially stopped supplying spare parts for my MacBook Pro Mid 2010 to its authorized repairers, and AFAIK there is no way to buy genuine Apple parts on the market.
I would ensure that you purchase a battery from a reputable online store dealing with Apple products.

For example, the following are some well-regarded sites:


Mac Sales 
Simply Mac
RAM City
Macfixit


By buying from a reputable store you'll be sure to get a battery fit for purpose, regardless of manufacturer. Being reputable means they're only going to sell something that works and they'll stand behind the product they sell, regardless of the brand.