Affection
Ignoring the odd romantic relationships, there can be two kinds of love a raider may have for her raid leader. The most desirable of the two is what I am going to call affection. Affection is a state of strong positive emotions for another human being, commonly found in friendships (and yes, romantic relationships.) As a raid leader, it is very useful to have a circle of players with deep affection for you that will support your actions, even if you make mistakes. This will be players that you can trust with special tasks and that you can talk to about problems you have. These players will also keep you up-to-date with any issues they see creeping up inside the guild and that will defend your decisions against others.
One thing that you have to be careful of, though, is not to show too much favouritism. These people like you for your personality and maybe your common past, they don't need to be treated in a special way to stay close to you. Other players that don't belong to this circle would feel treated unfairly, be unhappy, and maybe even end up in a state of hatred.
So we have established players with affectionate feelings for you are a good thing to have, but most humans tend to want to be liked anyway. Ideally I would be able to give you a guideline here, detailing how you can make all your raiders love you deeply. I can't do that for two reasons. For one, I believe it is impossible to have a close relationship with all your raiders - unless maybe in a very small ten men raiding guild. If you raid with 25 people (plus the usual replacements), there will be players who you like more than others and there will be those who like you more than others do. What's even worse, human relationships are incredibly complicated and I'm ill equipped to tell you how you can actually make them work. Different people like different things in a friend, one single person may even like people with greatly differing personalities. The only advice I can give on affection is - do what you always do and keep your friends close. Just don't keep them so close that others feel left out.
Shallow Love, or Happiness
Fortunately - for both you and this article - there is another type of love in play here, the one resulting from happiness. I talked about this briefly in my Fear, Love, Hate post when explaining Machiavelli's quote. This love is far more shallow and can maybe be compared to the love a cat has for its owner. The cat doesn't care about the owner's personality, it cares about being well fed and petted from time to time. If you do that, the cat will stay with you and love you for it.1 If you stop doing it, it will moan for a while and then likely leave you to find greener pastures. Raiders work the same way. As long as you give them what they desire, they will stay with you and pledge their never-ending loyalty. When you stop doing it, well, other guilds have rogue spots too.
Even if there is a risk of losing raiders that you bind to yourself this way, it is a very valid thing to do - I would even say necessary. Your group of core friends that will stay without any incentives will be too small to successfully raid and, unlike rulers in Machiavelli's time, you don't have the power to force them to raid with you. If they want to leave, they leave. It is therefore pretty much essential to "feed" your raiders regularly in order to make them love you or, by proxy, the guild.
Now it may be easy to say that you don't want players with this attitude in your raid, but it may be far too widespread for you to weed out. Personally, I like progress and I join as many progression raids as I can. That doesn't mean that I don't hate it when I have to sit on the bench for a farm raid. When you set your progression targets you need to make sure that your players still get enough loot to be happy but you also need to ensure that you have enough progression to always provide new and exciting loot.
Public praise makes people feel even better (in most cases), but has to be used with care. Telling a tank that single-handedly saved your raid from wiping how well he did will make her very happy. If you give out public praise to everyone all the time though, nobody will take it seriously anymore. I witnessed a prime example of this when I studied in the states for half a year. At first I was very happy when my 3D graphics teacher told me my work was awesome. Then I realized he said the same to everyone, even the most atrocious pieces of work got an "Man, that's awesome!" from him. From then on his praise was worth exactly nothing to me, it even made me feel bad as it implied that I was as bad as everyone else around me.
Mass praise is the least controversial to give out, but also the least effective. Congratulating your raiders on a job well done from time to time will keep morale up and will indeed make them love you more (as opposed to hating that grumpy raid leader and her criticism), but doing it too often or in the wrong moment will greatly devaluate it. There are only a few things worse than a raid leader saying "Good job guys, keep it up!" after an absolutely atrocious wipe. You raiders aren't completely stupid, don't try such obvious lies.
I'm not saying to never do someone a favour, but don't use your position as a leader for it. Rather tell people that you would love to help them but that that would be unfair towards others. Most people will understand. It can be hard not to take a good friend to a raid that she wants to go to, but you have to distinguish between yourself as a player and yourself as a leader.
There are two things you will always have to keep in mind when relying on shallow love. One is Machiavelli's warning that love only holds until problems arise. People that love you (or your guild) for the progress, will leave you if the progress stops flowing. Your raiders are like cats, make sure you are willing and able to feed them before getting one.
I will leave you with a longer quote of Machiavelli's second warning, so you can enjoy some convoluted writing. In essence he's telling us that, in trying to appear completely liberal, a ruler will use up all her fortunes and will have to fall back on unpopular measures to stay in business. If you are nice to everyone, you soon won't be able to be nice to anyone anymore. It's better not to try to appear overly friendly so that you can actual afford being friendly from time to time.
"I say that it would be well to be reputed liberal. Nevertheless, liberality exercised in a way that does not bring you the reputation for it, injures you; for if one exercises it honestly and as it should be exercised, it may not become known, and you will not avoid the reproach of its opposite. Therefore, any one wishing to maintain among men the name of liberal is obliged to avoid no attribute of magnificence; so that a prince thus inclined will consume in such acts all his property, and will be compelled in the end, if he wish to maintain the name of liberal, to unduly weigh down his people, and tax them, and do everything he can to get money. This will soon make him odious to his subjects, and becoming poor he will be little valued by any one; thus, with his liberality, having offended many and rewarded few, he is affected by the very first trouble and imperilled by whatever may be the first danger; recognizing this himself, and wishing to draw back from it, he runs at once into the reproach of being miserly."- Nicolo Machiavelli, The Prince - Translated by W. K. Marriott
UPDATE: Don't miss part 3, where I finally talk about respect (and bring the series to an end.
1Gevlon, of Greedy Goblin fame, put a post up on the topic of buying friends in WoW today. This is pure coincidence, I promise. Go read it anyway.
2 Clearly, all resources are somewhat limited or they would be worthless. An unlimited resource in this context is one that is never fully spent. If you have a rich guild bank for example, you can reward your raiders with flasks or paid-for repairs and you will be able to reward anyone that's doing well, without taking things away from others. Unlimited bonuses always come from previously unassigned or unused resources.