There is no definite answer to this, and is a debate.
By the way, the 'Middle East' is not a nation.
In my opinion, it would be every country, including my own, because we are corrupting ourselves, destroying the planet, and I fear we are in a verge of WWIII (About the whole nuclear warheads factor - more countries are now geting nuclear weapons, agains the United Nations 'law').
Or, it may be no nation, but the goverments themselves, and the the civillians.
Switzerland.You get fined for rolling over birds and they hate fast and gas guzzling cars i.e. Bugatti Veyron.And it sounds so boring.On the positive side motorways that double up as a runway for military planes.The swiss are so peace loving and neutral so why would they want something in the event of a war.
I would say China. They have no feelings for anybody or anything, both human and animal attrocities, Tibet the biggest one in the world but of course larger countries have nothing to gain so did nothing including UK. Yep I say China who also add to the larger pollution debate.
Saudi Arabia. Still living by a medieval law that primarily punishes the poor, immigrants, women and anyone who doesn't follow the rules as laid down by Shia law - except the leaders who own anything they want, including mansions, yachts, cars in all parts of the world and spend most of their lives in Monaco so they can gamble and hire expensive ladies, whilst going back to Saudi about one month a year. Probably to wact ha good old traditional beheading. A racist, sexist, arrogant people, who hide atrocities behind benevolent trickles of oil and arms trading.
There is no 'worst nation' per se. Nations consist of people of all types; saints, sinners and everything between.
The rulers of some nations can be, and are, reviled, e.g.
Kim Il Sung, Robert Mugabe, as were Adolf Hitler and Joseph Stalin in their day. So far as the people are concerned however, they can't all be evil just because their rulers are psychopaths.
No 'best' nation, no 'worst' nation, just people.