Hello fellow trainers!
Lifesteal and Auto Heal are easily the 2 best healing bonuses in the amiibo metagame. Both are very effective at turning a match around or keeping it one sided. But despite being remotely the same yet very different at the same time, it can be tough to choose which is best for your amiibo. I personally prefer Lifesteal because I train my amiibos to be very aggressive and try to finish a match with as a big of a lead as possible. However, some of mine tend to extend matches to sudden death very frequently making Lifesteal useless to them since they don't hit their opponent much. Of course, those are the advantages to a character with Auto Heal. If paired with a good bonus effect like improved dodge ability, it can hover around 0% for the entire match if they can finish it. And that would mean making them think almost 100% defense than landing a hit on their opponent.
In the end, it really only comes down to your style of training. Lifesteal for the aggressive, and Auto Heal for the defensive. But what do you think of the topic? You have my ears.