Roblox and Blockland both have nearly identical replay values. I, personally, prefer Blockland to Roblox, as Roblox has a semi-handicapped community and a lag problem. Blockland has some problems as well, but I can't think of any off the bat. To quote Choneis, there is no war, only people who think there is one.
I don't really mind with the community, Just Game Play.
I really don't like it when I backfire 1 checkpoint (Usually nicked "CP") when I got bloxxed (A.K.A Die) on a Obstacle Course (Obby) .  By that, say that you're at CP 4.  You're bloxxed and a part of you make contact with CP 3's spawn point.  Frustrating if it happens too many times.