I know a few people from Jet2 who went to Ryanair, but that’s neither nor there I guess as I wouldn’t touch Ryanair with a barge pole, especially in the current climate.
I’ve worked for TUI and Jet2. Personally, TUI suited me better. I know it’s horses for courses, and Jet2 do have their plus points such as a quick command, but for me, the variety of flying (long haul, Canadian detachments etc), rostering agreements, part time options, and overall terms and conditions were significantly better when I worked for TUI.