I prefer
Erika over
Linda, but I don't really have an Erika/Erica preference.
Linda feels a lot more dated, and is the name of one of my mum's friends, which means my main association for the name is a middle-aged mum of two (rather annoying, I must admit) kids.
Erika feels a little cooler.
Erika conjures up images, and I have no idea why, of a cool girl at a skate park. I'm split on the spelling - on the one hand,
Erika can seem a bit of a "kreatyve" spelling, although not heavily so, but
Erica also feels a little bland.
Erika has a lot more character to it.
If I had to put a colour to each name,
Linda would be a kind of warm orangey-brown, while
Erika's a bright purple.