These are $4.99 sampler trades that the off-brands will offer to entice new readers. Honestly, Vertigo is hardly some small indie company, though; they are merely an imprint of DC, who is owned by Warner Bros., so much like much other so-called "indie" stuff, this is merely marketed that way so that people who wouldn't buy something mainstream, i.e. DC, would buy this.
Fables was enjoyable enough, but maybe not enough to make me want to buy the series. I love the cover artist, whoever he/she may be. Invisibles seemed adolescent at best. I suppose if I were 15-21 it would "speak" to me. At 35, it's been there done that, grown out of it.
Lucifer was so-so. Again, I will keep my cash in fist for other things.
Preacher was good, although I am not rushing out to buy it.
Sandman Mystery Theatre was very enjoyable, and I did pick up the first trade of it and enjoyed it.