Guardians and Wardens Guide in LotroFor tanking classes, Guardians are your standard heavy armor(The lord of rings gold), sword and board class. They take a licking and keep on ticking. They also have a dps 'stance' called 'Overpower' that lets them solo decently. They have skills to acquire threat (agro) very rapidly or even instantly.
Guardians have skills that allow them to trigger conjunctions or 'fellowship maneuvers'. This is a really neat Lotro mechanic that lets all members of the group participate in sort of a super group combo. There are many of these and they do different things.
Wardens are medium armor tanks that have an interesting mechanic called a gambit. A gambit is a series of strikes using spear/shield/fist combinations. They start at length 2 and go up to 5. Wardens are a pretty good solo class and can take on a very large number of mobs. Since you have played tanks before, we would suggest trying a warden first since it is probably different enough that you will love it or hate it.
If you love it, stay with it, if not, fall back to a guardian. One of the warden's skills allows them to quickly remove corruptions from mobs. Corruptions are mob buffs or player debuffs that can be 'very bad' if left unchecked. All classes have some sort of corruption removal skill, but wardens are really good at it.
Generally Race of Man has slightly better racial attributes (for a tank, the +5% incoming healing bonus, +1% Block/Parry/Evade bonus and the emergency self-heal are very good). To the extent any race is disfavored as a tank, it is Elves, but none of the racial attributes are so dramatic that they overly hamper a player. We recommend you to buy Lotro powerleveling service from our site, you can buy them at low price as you need.