I suppose Immortal should be anyone's first stop, as they really do cover the entire bandwidth of the genre, from short blast orgies to symphonic epicness. You might want to try their 1999 album, At the Heart of Winter for a start. You should find something to like there, especially if you enjoy thrash metal.
If you want a more upbeat type of black metal, if that is even possible, try Vreid, especially Milorg, Pitch Black Brigade or I Krig. Vreid have been called "black 'n' roll", which may also be easy to digest for newcomers. I also suppose this is a case of "if you like Enslaved, you will love them".
Dark Funeral is about as catchy as black metal can get. They put out a pretty good live album, called De Profundis Clamavi ad te Domine (most of their albums have Latin titles, which caused a classics professor to ring them up one day and offer them to translate the titles for them in the future so they'd finally get them right). Caution, however. If Immortal and Vreid are only very dark, Dark Funeral does advocate a lot of what black metal stands for, including Satanism and sometimes rather sick lyrics.
I've always been of the opinion that Naglfar (not to be confused with Nagelfar) are a band that Maiden fans will find a lot to like with. They have many Maiden-inspired riffs and melodies, so they may also be a good starting point.
You might also think to yourself, "to hell with melody and epicness", and want to find black metal's equivalent of a punch in your face, in which case I'd direct you to Marduk, especially their album, Panzer Division Marduk (now playing). Best listened to on a Monday morning with a cup of strong, black coffee.
One of my personal favourites is Geïst (now known as Eïs). They have all-German lyrics, but if you listen to this genre with the expectation of understanding the lyrics in general, you are doing something wrong. Their 2009 album, Galeere, is nothing short of an epic, dark masterpiece.
EDIT: If you can stomach their very misanthropic lyrics, you might also find something to like with Dissection.
EDIT 2: If you already enjoy death metal, even melodic, there are a few bands at the black/death cross section that might ease you in, such as Impaled Nazarene or God Dethroned.