I really like the chaos communication congress in Germany. It has a nice mixture of technical talks societal talks. Most of the talks are in English, but there are some German ones as well. They're really good at uploading videos quickly as well, so if I can't make it to go in person, I just watch on YT.
I like Ohio Linux Fest (https://ohiolinux.org/) even though I have to fly across the country to attend it. It's cozy and it's got heart. I remember having breakfast with Ethan Galstad (Nagios founder) a few years back, and he keynoted it last year. They had some great speakers last year, a father-daughter entrepreneur pair (Joe and Lily Born). It was lovely!
Even as someone who had never written a line of Laravel in my life when my company sent me, I was welcomed and found that I could understand many of the talks. Some, of course, sent over my head, but there were others there who really got alot of of those as well.
It's very niche to one open-source CMS, and it's not even the major one, but I'm a fan of the Umbraco UK Festival. It's one day in London with a bunch of talks, and a ton of socialising.
LambdaConf is small midwest conference focused on Functional Programming. Wonderful mix of beginner workshops, advanced talks and everything in between. Childcare on site, nice venue, wonderful food and a lot of really enthusiastic people willing to chat and discuss various topics of interest.
I still love the pilgrimage feel of giant spectacles: walking the floor at PAX, GDC, or E3 is sensory overload and I'm addicted ;) Goal is to attend one of the offshoots in Asia such as PAX Guangzhou or GDC Shanghai. And someday the grandaddy of them all, the Tokyo Game Show!
I enjoy defcon. I've been going for nearly 20 years and it's changed a lot, but dark tangent (guy who started it) has kept it pretty honest to the hacker ethos. I've heard shmoocon is good too, but it's sold out every year I've wanted to go.
dcdevfest: this was a great conference right in the midatlanti area in the capital one hq. was really a good crowd interested in a bunch of deep tech talks. nice facilities, not much in the way of vendor space.
aws reinvent - really always enjoy this because it's really the big event of the year. everyone who's involved in technology/cloud/whatever shows up to learn, pitch and hang out. there's some feelings of traditional "trade show" buy there's value in the whole experience. vegas is a bit much.
mongodb world - a good event if you are specific to this market. workshops are helpful.
selfish plug for a product conference I co-organise in the UK called Canvas. We try to find speakers doing the actual hard behind the scenes work building amazing products. http://canvasconference.co.uk/