Any one that you feel comfortable with. The major names have not changed much: RedHat (and its derivatives), Debian (and its derivatives), Gentoo (for the hardcore), and SUSE.
Some new challengers worth looking into are Ubuntu (Canonical’s take on Debian unstable with a unique NIH-syndrome spin), ArchLinux (The hipster distro that claims to be as hardcore as Gentoo and Slackware without requiring source compilation. It also has derivatives like Manjaro that are more user friendly), T2SDE (the logical next step of Rock Linux used more as a development environment), Alpine Linux (meant for embeded and base systems to build from), Void Linux (once you enter the void you know immediately if it is for you or not), and QubesOS (a secuirty based distro focused around sandboxing everything in containers and VMs).
OpenSolaris is pretty much dead after Oracle bought Sun Microsystems. It is basically on life-support updates. It lives on as the OpenIndiana project but, I have not heard much over the last two years. I think they are still on the Hipster kernel release.
Xen is still a thing but qemu/libvirt have pretty much taken up that space due to built in support and close integration with the Linux kernel virtualization extensions.
Boy is it an exciting time to be alive. No only can you do this, but you will want to look into the Looking Glass project here on these very forvms to get the best, low latency performance.
Wendell has covered openRDP and freeRDP integration into terminal services. IF you wanted to do VDI, then you really have to stick with Citrix as they pulled a Microsoft and out-Microsofted Microsoft on their own terminal services extension. Citrix is going to get you the best experience that you can get with VDI, but you will have to pay for it.
Welcome back to the fold. That is why these here forvms exist. Happy tech-ing.