Better regarding what? Depends on what you want. AFAIK, Whonix is focused on anonymity by using Tor as an integral part of its architecture. TAILS has the same goal but is designed specifically to be run from removable media and to leave no trace on the host system after it's done, much like using a live CD. Qubes is focused on security through isolation by means of an hypervisor. Whonix can run upon Qubes, beside others of course.
EDIT: if you want as foolproof of anonymity as possible it seems that Whonix holds an edge over TAILS and both are better than Qubes. Because Whonix routes all network requests through a locked down gateway VM, there is less chance that any program or system component can escape the Tor "funnel" than in TAILS and particularly Qubes, which focuses on security primarily.
I see, thank you. I want this to be running off a removable drive (although, realistically, I'll probably just keep using Tor Browser as I don't really do anything much with it), so I'll either use Tails or see if Whonix can run off a USB disk, thank you.
Whonix is a pair of Debian instances. One is a Tor gateway, and the other is a workstation. The Tor gateway isn't a router, in that it doesn't route packets. It just exposes Tor ports on a shared private network. The gateway and workstation instances can be run on separate hardware, as KVM or VBox VMs, or in Qubes.
Some years ago, I managed to build a LiveDVD with Debian OS, VBox, a pfSense Tor gateway VM, and a stripped-down Whonix workstation VM with Openbox. But it took ~20 min to boot :(
EDIT: if you want as foolproof of anonymity as possible it seems that Whonix holds an edge over TAILS and both are better than Qubes. Because Whonix routes all network requests through a locked down gateway VM, there is less chance that any program or system component can escape the Tor "funnel" than in TAILS and particularly Qubes, which focuses on security primarily.