Nixon opened Russia and China to US diplomacy. He extracted us from the Vietnam morass (never mind the details). He also strengthened environmental protection, improved human services, and prosecuted a more humane and successful fight against drugs. In fact, if you are able to overlook certain, well, let's call them indiscretions like criminally abusing the Constitution and committing war crimes, Nixon is one of our best presidents.
Although close associates (Kissinger, for one) report that Nixon was delusional before he resigned, at least he was willing and able to grapple with reality during most of his term. Contrast that with the current administration, which has never met a fact it didn't think it could spin. For these sub-urban cowboys, “realpolitik” is a funny word, probably French, that labels you (horrors) as a policy wonk.
Some members of this administration and their toadies were until recently absurdly talking about W as a candidate for one of the best presidents ever. You know the argument, “brought democracy to more people than anyone since...” then they were usually stumped because they don't know nothin' 'bout his-tor-y. Now, mired in Iraq and Afghanistan, with deficits mounting and the social fabric only a memory, most would agree that W will be sounding the bottom of the barrel of the worst presidents.