It’s a toss up which is more important and powerful, love or gratitude.  You need both for the Law of Attraction to work well.

Now when I say love, I’m not talking about a superficial love, like I love oranges, or I love sleeping in on the weekend.  No, what I’m talking about is the deep felt feelings of love, both for others, and most importantly with yourself.

If you don’t feel love towards yourself, then you’re never going to feel worthy to receive anything. You’re at best only going to get lukewarm results.  At worst, you’re going to get negative results.  You see this with people in bad relationships.  Somewhere deep down in their subconscious or unconscious, they don’t love themselves, which usually works out to not feeling good about themselves or not feeling worthy to have anything good in their lives.  It’s what I feel causes low self-esteem.

By the same token, you really can’t have a healthy love for anyone else until you love yourself.  You can’t give what you don’t have.  I think you’re also not going to be able to receive what you’re not familiar with.  Something is going to be tainted when it goes through your unconscious filters/beliefs if you receive love when you don’t love yourself.
I’m also not limiting this to love like I love my significant other/partner.  I’m also including things like the love of a child or parent, the love of a beloved pet, the love for someone you respect, and love for your fellow man.

When you can learn to love yourself and your fellow (wo)man, then you open yourself up to receive good things into your life.  You’ll radiate love, and the universe will respond in kind and love you back, bringing your heart’s desire.