Depends, what kind of metal do you like? If you're just starting out, I'd suggest:
Amon Amarth - Deceiver of the Gods: It's really as catchy, awesome, and as accessible as Death Metal gets. To be fair, this isn't death metal. This is Iron Maiden with screamed lyrics about Thor and Odin.
Opeth - Ghost Reveries: You probably know Opeth already, but in case you don't know which one to pick, I suggest this one. It's got more 70's prog and latin flavour to it, and it's got a great deal more clean singing than Opeth's other album's as well.
Agalloch - The Mantle: My second favourite album of all time. It's part neofolk, part post rock, and part black metal. There's a lot of acoustic stuff but also a lot awesome metal. They tie together really well, to the point where it almost feels more like a heavy folk album than a nomal metal album.
Moonsorrow - Voimasta Ja Kunniasta: I don't know anyone who doesn't like this band. They're epic. If you like fantasy, this is your band.
Isis - In the Abscence of Truth: The best post metal album ever made. Bar none.
In Flames - The Jester's Race: Warning: Don't listen to any of this bands new stuff. It's terrible. However, this is my all time favourite melodic death metal album, and a great place to start with the genre.
Death - Symbolic: For old school death metal, you cannot go past this album. This is back when death was basically just a heavier version of thrash - there are no cookie monster growls, just awesome riffs and aggression.
Negura Bunget - Om: Negativity towards this album doesn't exist. It's a masterpiece of progressive black metal.
Cynic - Traced in Air: There are some people who don't even think this album is metal - but it is, and it's dope.
Swallow The Sun - The Morning Never Came: Doom metal at it's finest.
Most of these albums were chosen for accessibility. They're all produced fairly well, most of their lyrics aren't disgusting, and most of them either incorporate other styles, are more melodic than most, or are just straight up catchy. Hopefully you enjoy something there.