I've been with a U.S. based major oil & gas corporation for 30 years (background), and found AUVSI and more so, Energy Drone Coalition to be the best for O&G type of "Energy". Which types of energy are you interested in?
The biggest benefit of these two events for me are the seminars, training sessions, and panel discussions. I'd say I spend 90% of my time in sessions and 10% on the product floor. I've been attending for the last 2-3 years for both, and have been asked to participate on panels. Great experience.
There are lots of opportunities to create new networks for learning or getting involved. ALL of the leaders in this space attend both these events. That includes everything from regulatory (FAA, LLE), Education (University robotics programs), major OEM's, and major users. You can easily meet up with a guy who has been doing real estate photography, or someone who is flying a Jump 20 at an FAA test site. All are there.
The OEM / service provider floor booths are a great way to keep up with the technology and advancements from software, hardware, 3rd party bolt-ons, and new, emerging tech (vehicles, communications, flight control, payload sensors, safety gear, etc.).
AUVSI switches venues each year I believe. Last year was Denver, this year is Chicago. Energy Drone I think is always in Houston (last 2 years anyway)
Hope this helps a bit, but happy to answer more questions if I can.