I already reviewed the two "Battle for Middle-earth" games separately (see their individual pages for details), but I am voting for this one because it includes the "Rise of the Witch-King" expansion for "Battle for Middle-earth 2". This expansion improves the game enormously. :-)
As for "the Battle for Middle-earth" games? There is so much to cover! The first game, LOTR: Battle for Middle-earth, allows you to play as members of the Fellowship as well as Rohan, Gondor, Isengard, and Mordor. Like all RTS games, you can build a base, train units and try to take your opponent's base - but there is much, much more to this game. You travel through Middle-Earth, seeing the sights and getting attacked by your enemy (and you can play either the "Good" or "Evil" side). The attacks come relentlessly, so almost from the start, the game puts you under pressure. It's up to you to resist the attacks, drive your enemy back, and go on the offensive -- either to free Middle-Earth from Mordor, or to crush it under your armoured boot! :-)
In "Battle for Middle-earth 2", you can explore what happens in Middle-earth while the Fellowship is off doing their own thing. There are more factions (e.g. Dwarves, Elves, Goblins etc.), and you can also hunt for Gollum and use the One Ring to ... whoops, I won't spoil it. :-)
In the expansion, "Rise of the Witch-King", you travel back to the Second Age and see the rise of the Witch-King of Angmar. You might remember him: he fights Gandalf in Gondor, and slays King Theoden, only to be slain by Eowyn and Merry. But who is this enigmatic figure, and where did he come from, and what did he do before the War of the Ring? This expansion answers your questions, and is very fun too.
In short, I recommend this game very highly. Two thumbs up, way up!