I use BBEdit for C++ development, but it's more an editor than a full IDE. Depending on which IDE features you rely on, it may have them. I tend to turn most of that stuff off because I find it distracting.
I use PyCharm for python development, and they have tools for C++ and C# (and probably Java). It's generally unobtrusive and does a good job of giving visual cues for typos or whitespace issues which is helpful. (have a look at
https://www.jetbrains.com/ ) I tried their C++ IDE out back when it was still in Beta and wasn't impressed, but I'm sure they've improved it.
Years ago, I used NetBeans for C++. It was originally designed for Java and might have support for C# now. There were some problems with a few releases made after Oracle bought Sun, and I quit using it. I have no idea what it's like now. It was kinda bloated, but not nearly as bad as Eclipse.