What is a reasonable VPN-solution today?

We use a VPN-solution from CheckPoint which requires Active/X or Java in a browser. This was always troublesome for some operating systems, and with the release of Firefox 52 (which does not run Java-applets) it just gets worse.

What is a reasonable VPN-solution today? It MUST support Windows, it SHOULD support Linux and MacOS, and i guess it SHOULD support mobile devices (iOS, Android), too.