Hardest major would probably be England I think- they don't seem to have as much VP potential as the others........
Austria is not very hard in 2.2 IGC, I'll have to try in IGC 2.3- Austria has a huge potential for diplo-annexation, and it has a good oppurtunity to rack up tons of VPs by force-converting the North Germans to Catholicism when it's counter-reformation time. What enabled me to kick Turkish Ass in my game with it was an alliance with Poland. At first I moved to diplo-annex as much as possible, then I allied with POland, and Turkey apparently has trouble when fighting both Austria and Poland at the same time.
France is easy providing you play it right, if you play bad it is easy for Spain to beat you. Spain is your key-enemy, and the key to the Franco-Spanish wars is the minors in west Germany and Italy. In my first game as France I ignored my minor allies and concentrated on getting land from Spain. In spite of siezing Flanders early, winning most wars with Spain, annexing the Netherlands, and annexing the Aztecs, Spain dominated Italy and got huge land in west Germany, and had minor support, and eventually got the upper hand. Next time around I supoprted my minors, and tried to annex any minor foolish enough to ally with Spain. Also stole the Spanish map and siezed Andalusia, annexed the Axtecs, and stopped early because it was clear I was kicking too much ass and I would clearly win....
Portugal- Portugal is very much winnable. They key is to annex the Incas early, thus giving your dirt poor country some need economic base. Move into Asia, put up a bunch of trading posts- especially in India, grab everything there so that nobody else can go there. Then get as many colonies in India as possible- those colonies typically give $20 taxation income and $40 trade income- with that you can get the economic VPs to win, especially if you manage to annex any Indian countries.
I am playing Poland right now, and it doesn't seem to hard. I am playing very agressivley agaisnt Russia, who I see as my greatest security threat. I attacked them early when they first moved Against Kazan, then annexed Pskov and siezed Novgorod. I've held a policy of opposing them whenever they try to annex a Khanate- though sadly they still grabbed Kazan. I also allied with Sweeden to help me against Russia. I think I have siezed 5 provinces from Russia now, and hopefully I can deny them their edge and keep stealing land from them-perhaps I can eventually annex them. I also allied with Austria an Bohemia(the latter will soon be diplo-annexed by the former just as Hungary was). This should help against Prussia(playing United Prussia mode for more of a chalenge), who sadly managed to sieze Silesia. Hopefully the Austro-Polish alliance will stop threats from Turkey and the Protestants of Northern Germany and the Baltic, and for now I seem to have a strong upper hand over Russia.
The problem is, even though Poland is pretty secure, it'll be hard beating Spain in VPs.
As for Minors- I strongly reccomend the Mamelukes if you are up for a challenge, as them I managed to conquer all of North Africa except Tangiers, and sized all of the Middle East and some land in Greece as well. VERY hard getting the upper-hand over the Turks at first though, who you will lose land to at the start.
Also try Venice, one of the most fun countries. Brandenburg is also an awesome country, huge diplo-annex potential...
