I got an Earth:Final Conflict vibe from V even though I've only seen a couple episodes of E:FC and have never seen anything V related.
Whew! Youngster!! There are massive similarities, but equally, "Apparently friendly aliens arrive, but prove to have a hostile ulterior motive" is no more copyrightable than "Boy meets girl, there are problems due to family and friends." It's what you do with it that matters. V (original version, initially) was about the arrival and how people adapt to it (and become suspicious about it), and eventually about an openly hostile occupation; E:FC began several years after the Taelon arrival, when they'd become a part of everyday life in spite of people's suspicions. Enough of a difference for both series to be good in different ways, at least to start with (before they both start going silly later on).