With the revamp of Evendim, you pretty much need to choose between North Downs and Evendim; they cover the same levels.
Evendim is a seamless leveling experience starting from around level 30 in Oatbarton and ending in Annuminas around level 40.
North Downs has not been revamped, so you might find quests that are over or under leveled for you as you quest through, but it covers a wider leveling range: about 21 in Trestlebridge to 42 in Esteldin (quests range from 26-42 in Esteldin).
Finishing either Evendim or North Downs will put you at the right level to start Misty Mountains about 39 at Gloin's Camp (be sure to stop through Rivendell if you haven't already). Quests go all the way up to level 48-50 with the High Pass and Goblin Town, but it's not a smooth progression, and you will probably need supplemental XP through skirmishes or bouncing to other zones like Angmar or Forochel.
Eregion starts at level 48 and is seamless into Moria, which is also seamless thanks to the recent revamp.
[CENTER][SIZE=1]MINSTREL and member of the vocal minority[/SIZE][/CENTER]