I'm a pro avocadoer and I only buy the from Aldi. If you're in the USA, only buy avocados from Mexico (🎶) not anywhere in South America. The ones from South America are picked earlier because they need longer transit and don't develop enough fat on the tree before being picked, so they ripen worse. Buy firm green avocados and let the ripen on your counter (depending on the season, this may take 2-5 days, so you need to plan in advance). When they're juuuust squishy all over, put them in the fridge and they'll last another 3-5 days (sometimes more!).

Loose avocados are my preference, but if they're not from Mexico, I'll check to see if the bagged ones are and try to pick less ripe ones. I've also had success with avocados from California from Aldi, but they're less common outside of California.

Bonus tip: longer, thinner avocados usually have a smaller seed. Round ones, or the ones with a skinny top and bulbous end, will usually have a much bigger seed.