either will work good. which looks better mmmmm, build both ways and take pics, hehehe, thats the only way to know which looks better
decisions decisions....just keep the stability and flow in mind-whatever way it comes outs you know it will look good. O also keep in mind you will be moving things around here and there when you place corals, leave some good ledges/flat spots/cubby holes for coral placement. some corals come attached to rock others in mates some grow up others grow out ect...and all grow different so you will be making room later anyway.