I usually don't use any victory conditions. At some point I realize the ai players are so far behind that I can win whenever I want, it is just facing the multi hundred turn slog to get to the victory screen is tiresome, so I start a new game.
Influence though, is so powerful from the middle of the map that now I only play from the edge. Otherwise I have all the ai players choked off and isolated too fast.
Also remember being in the middle gives you a practical scanner and speed buff. If going from the middle to the edge is 100 tiles then going from edge to edge is 201 tiles. You need twice the scanning and speed to attack your farthest enemy from the edge. This means slower response times with ships built at your core planets. If you have an insane 70-speed warship, from a shipyard in the middle it can attack over 75% of the map on the same turn it is built, And it can hit any tile on turn 2. If the same ship is built on the outer rim less than 40% of the map is in range on turn 1 and some of the map can't be hit at all until turn 3. In late game wars these factors give the middle a huge advantage.
So the real trick is knowing if you enjoy a challenge early go middle. If you enjoy a challenge late go edge.
