Apple's M1-equipped $999 MacBook Air is our top recommendation for the best MacBook overall. The Apple M1 chip makes it faster than we ever expected the Air to get, and its power efficiency enables much longer battery life, lasting over 14 hours on a charge.2 Jan 2022
Is the 2015 MacBook Air still good in 2021?
No, not unless it's priced really, really well. The new MacBook Air M1 is much faster than the 2015, has a better screen, and will have a brand new battery, and it's priced competitively. Unless you can get that 2015 for around $300 or less (US) it's really not worth buying.
Is a 2012 MacBook Air still good?
My subjective opinion is that yes, any 2012 Mac can be very serviceable today. By 2012, Apple's minimum RAM in their new machines was 4GB. That amount of RAM is still plenty for performing many tasks today. MacBook Airs since 2010 have always included an SSD, so that's covered.