Would go with Samsung S2, however might get flamed but Apple Iphone4 , "Nokia" failing to connect people.
I would go for Samsung, FOR now. However Nokia is getting back with Windows. Let's see how that goes.
Now I go for Samsung Galaxy S II but I also want to take a look at the Lumia 800 windows phone of Nokia
If you are serious business user then go with blackberry or Nokia. Samsung kia software for sync is a nightmare and it doesn´t even install properly let alone work properly.