An interesting topic. Here is my take on the GC:
THE MAJORS
Spain - Easy as Breathing. Only fun if you want to literally take over the world, or if you want to be the bad guy in a multiplayer game. Prepare to spend a lot of time expanding your colonies.
France - Extremely Easy. Same basic feeling as Spain, although the colonial empire is optional. Nice to write some alternative history though: Go protestant, out-colonize the Limeys, crush Spain. Still, not recommended outside multiplayer.
Portugal - Easy. The primary colonial nation. In order to survive you must build a thriving colonial empire. If you feel adventurous you can attack Spain when she is fighting France, but I would recommend having good relations with Spain until you are sure of victory. Personally I don't like the extreme focus on colonization - not my cup of tea.
England - Very Easy. Quite fun to play, even if it is a little too easy. Annex Scotland right away, get some colonies going and build those cheap fleets up. Nothing will ever threaten you. There are plenty of more enjoyable nations to play.
Turkey - Very Easy. Infantry costs next to nothing and you are rich, but you are also surrounded by hostile nations and will likely suffer from technology retardation in the late game. Don't get overconfident. I like playing Turkey, but when all is said and done it is just too easy.
Poland-Lithuania - Easy. Surrounded by enemies and with little hope of gaining colonies, Poland is harder than one might expect. However, she is rich and has very cheap cavalry, which means that once one of her principal enemies has gone down the challenge is over. I usually begin by cutting off the Russian path through Siberia, then crush the Teutonic Order, then take Novgorod. After that you have basically won. Fun, but too easy.
Russia - Very easy. Your nation is not especially rich in the beginning, but her location and cheap infantry make her a winner. Once you have annexed the Khanates (which is easy) you are unstoppable. End of fun.
REGION-SPECIFIC MAJORS
Austria - Easy. Austria is rather rich, has good leaders and a good chance of annexing Hungary peacefully. Besides, your monarch is very likely to be elected Holy Roman Emperor. Diplomatic annexations in Germany should be a piece of cake. Once you have added Bohemia and Hungary to your domain the game tends to become less fun. Still, it is rather fun.
Sweden - Normal. Sweden is IMO the most fun of the majors; she has a tough position, squeezed as she is between two enemies, she starts out in vassalage with stability -2, and her economy is weak. Yet she has plenty of good leaders and a plethora of fun strategic options. To maintain pace in the tech race you will need a rich trade empire, so get those colonies going ASAP. In the end though, even Sweden is perhaps a little too easy once you've mastered the tough start.
Denmark - Normal. Playing Denmark is similar in feel to playing Sweden, but your diplomatic situation is better and your leaders are weaker and fewer. Take the CoT in Holstein (Mecklenburg in the IGC), then cripple Sweden. Then get the colonies going. Lots of fun. Recommended.
MINORS
Not sure if you are interested in these, but I want to recommend a few favorites anyway.
Brandenburg - Very Hard. Good leaders, weak economy, lots of powerful enemies. Take it easy in the beginning and don't get overambitious. You can grow fast, but a backlash will come and you will be sorry, believe me. Watch out for the Austrians. Once they get a border with you, they will probably soon attack you. Lots and lots of fun.
Venice - Hard. Your generic leaders are good, you get some top-notch admirals and you have a wharf. Your goal should be to unite Italy under your glorious flag, then cripple the Turk in Balkan. You also have the option to go colonial. I once made the Mediterranean into a Venetian Mare Nostrum. Highly recommended.
Papal State - Very Hard. Your generic leaders suck and you don't get any historical ones. The Pope is usually a weakling and everyone is out to get you. Still, there is nothing quite like making Rome great again. Recommended.
THE MAJORS
Spain - Easy as Breathing. Only fun if you want to literally take over the world, or if you want to be the bad guy in a multiplayer game. Prepare to spend a lot of time expanding your colonies.
France - Extremely Easy. Same basic feeling as Spain, although the colonial empire is optional. Nice to write some alternative history though: Go protestant, out-colonize the Limeys, crush Spain. Still, not recommended outside multiplayer.
Portugal - Easy. The primary colonial nation. In order to survive you must build a thriving colonial empire. If you feel adventurous you can attack Spain when she is fighting France, but I would recommend having good relations with Spain until you are sure of victory. Personally I don't like the extreme focus on colonization - not my cup of tea.
England - Very Easy. Quite fun to play, even if it is a little too easy. Annex Scotland right away, get some colonies going and build those cheap fleets up. Nothing will ever threaten you. There are plenty of more enjoyable nations to play.
Turkey - Very Easy. Infantry costs next to nothing and you are rich, but you are also surrounded by hostile nations and will likely suffer from technology retardation in the late game. Don't get overconfident. I like playing Turkey, but when all is said and done it is just too easy.
Poland-Lithuania - Easy. Surrounded by enemies and with little hope of gaining colonies, Poland is harder than one might expect. However, she is rich and has very cheap cavalry, which means that once one of her principal enemies has gone down the challenge is over. I usually begin by cutting off the Russian path through Siberia, then crush the Teutonic Order, then take Novgorod. After that you have basically won. Fun, but too easy.
Russia - Very easy. Your nation is not especially rich in the beginning, but her location and cheap infantry make her a winner. Once you have annexed the Khanates (which is easy) you are unstoppable. End of fun.
REGION-SPECIFIC MAJORS
Austria - Easy. Austria is rather rich, has good leaders and a good chance of annexing Hungary peacefully. Besides, your monarch is very likely to be elected Holy Roman Emperor. Diplomatic annexations in Germany should be a piece of cake. Once you have added Bohemia and Hungary to your domain the game tends to become less fun. Still, it is rather fun.
Sweden - Normal. Sweden is IMO the most fun of the majors; she has a tough position, squeezed as she is between two enemies, she starts out in vassalage with stability -2, and her economy is weak. Yet she has plenty of good leaders and a plethora of fun strategic options. To maintain pace in the tech race you will need a rich trade empire, so get those colonies going ASAP. In the end though, even Sweden is perhaps a little too easy once you've mastered the tough start.
Denmark - Normal. Playing Denmark is similar in feel to playing Sweden, but your diplomatic situation is better and your leaders are weaker and fewer. Take the CoT in Holstein (Mecklenburg in the IGC), then cripple Sweden. Then get the colonies going. Lots of fun. Recommended.
MINORS
Not sure if you are interested in these, but I want to recommend a few favorites anyway.
Brandenburg - Very Hard. Good leaders, weak economy, lots of powerful enemies. Take it easy in the beginning and don't get overambitious. You can grow fast, but a backlash will come and you will be sorry, believe me. Watch out for the Austrians. Once they get a border with you, they will probably soon attack you. Lots and lots of fun.
Venice - Hard. Your generic leaders are good, you get some top-notch admirals and you have a wharf. Your goal should be to unite Italy under your glorious flag, then cripple the Turk in Balkan. You also have the option to go colonial. I once made the Mediterranean into a Venetian Mare Nostrum. Highly recommended.
Papal State - Very Hard. Your generic leaders suck and you don't get any historical ones. The Pope is usually a weakling and everyone is out to get you. Still, there is nothing quite like making Rome great again. Recommended.