I inspected all my colonies yesterday and I always marvel that swarms work so hard. They outperform my regular package bees and my bred Italians and hybrids.
I believe feral bees are the best—maybe temperamental, and swarm a lot if you're not careful, but some of the hardiest all-around bees. They've adapted to all. As a commercial/hobbiest beekeeper with 50 colonies at times, I hope to adapt as a beekeeper as well and do right by my bees.
Amy and I only have 3 hives, and we've only ever had feral bees, but we sure agree about how hard they work. We did a small-ish honey harvest a month ago, then opened up the boxes again yesterday to find frame after frame after frame of capped honey.
The bees were very manageable, especially considering how much carnage and mess we were causing to their homes. We ended up stopping the harvest because we ran out of buckets to cram honeycomb into.
Here's the end result. These are some insanely hard-working bees.
Feral is the way to go.