I've owned laptops in the past that actually get better battery life under linux than windows. My current laptop is a $189 Acer Cloudbook. It gets ~ 10hours with the backlight set low. I accidentally left it on overnight (backlight off, no web browser) and it was at 20% > 10 hours later. The only power tuning is "sudo powertop --auto-tune". I run evilwm (so, not some heavy desktop environment like unity).
(Web browsing is painfully slow without noscript; I use it for light C++ and VNC)
Similarly, compiling flexibility didn't prove like important feature for myself also. It allows you to slim down package installations or compile them with different optimization flags, but in most cases you don't gain much by using them:
- smaller package installation (by turning off features not commonly used) in the time where disk is cheap and OS is not the biggest consumer of the disk space
- have marginally improved performance if you know when it's safe to crank up compiler flags (better leave this decision to package maintainers)
- have debugger symbols built in - if you happen to ever need to do this, doing it for the binary package is not that difficult; you shouldn't have source distro just for this use-case
Gentoo deffinitely excels in providing you with concrete reasons to deepen your Linux knowledge if you have it as a distro on your main machine, which can be both pro and con.
Most users will probably never need to do this, but I find it invaluable.
I maintain my own patches for dozens of packages in order to fix quirks/WONTFIX bugs, add features that upstream refuse to touch, remove intrusive/unwanted features that piss me off, etc, and being able to do this without also having to maintain my own deb/rpm/<some other package format> makes it much less painful.
It's also nice for applying emergency security fixes without waiting for your distro to pick them up.
- All modern distros can run virtualized systems. You just need to install your favorite virtualization software (VirtualBox, qemu, VMWare, etc.).
- No distros have good battery management, at least not really on par with Windows, and certainly not on par with macOS. This is just the unfortunate state of affairs with the Linux kernel. Some of it is due to lack of focus on improving that aspect, and much of it is due to the difficulty of programming power management modes for various bits of hardware (a decent amount of this stuff isn't well-documented, or documented at all, depending on manufacturer). Using "powertop" (on any distro) can help you figure out the things that are eating into your battery and can help you reduce usage. TLP, a set of tools for configuring your system better for longer battery life, can also help, and should be available on most if not all distros.
Personally I run Debian (stretch) as on my main dev laptop, and it's been working well for me for years (well, jessie before stretch existed). I used to run Gentoo years ago, but got tired of long compile times. The flexibility of compiling or not compiling certain features into software just turned out not to be all that useful for me.