all have crappy left backgrounds... Imo, make the right effects cover more of the left.. and change the clouds one to fit the coloring more..then it would own.. right side owns render needs depth =)
Background is horrible. Try smudging it around and then blending the render into it and it'll be good.
v2 and v4 are sweet. v1 looks like poopy in the bg. lol I like the city stock bg. very FF imo. ^_^ Gives the tag a cool feel.
V2 and V4 are the best, the circles are nice, but it seems you've just placed the render and effects around the render on a stock.