I'm an emacs fan. But when it comes to Java and big codebase (5+ developpers), JetBrain or Eclipse are just the way to go . They provide : code navigation and fast indexing (emacs LSP is just so slow), super integrated debugger, tons of predefined stuff to open common's file. They just more intelligence about your code packed in. With emacs it's all bare bones. So basically for me it's about big project == big IDE and everything else is emacs (which is a sizeable share !). Also, I'd say that Emacs makes my life much more pleasant too : the community, the license, the endless customization, the millions packages; that's part of my life too and the more "pro" IDE's just absolutely don't deliver on that side.
Have you tried setting up LSC on either vim or emacs? It does everything an IDE does, aside from a debugger. Compile time errors are highlighted as soon as you're done typing, and many other IDE-like features.
LSP provides the bare minimum semantic support (navigation, completion, inline error annotations and basic refactoring support) to make emacs or vim worth of consideration for serious coding at all, and only because the inferior code understanding both have even with LSP is often more than compensated by other advantages such as being able to work in a terminal compelling plugins like magit for emacs, or, at least in the case of vim, general snappiness. I like and use all three, they all have their pros and cons, but saying that LSP (via LSC or one of the other myriad of lsp-support plugins) is about as true as saying that Jetbrains + Vim plugin lets you do everything you can do with VIM.
BTW: emacs does in fact have a debugger: GUD (with a bit of tweaking, it's bearable, too).
LSC is just a language server plugin, right? That's not even close to covering what an ide like Intellij does, eg static analysis, code coverage, profiling, etc.
