Depends on what you play. On the WPN network you can find 6 max and some full ring Holdem no limit cash games. If you like the idea of the bad beat jackpot then they have that too. If you are a low to medium volume small buy-in mtt player there a few good tourneys frequently with overlay, but currently Merge has more volume and scheduled MTTs. WPN is also ok for heads up SNGs, however, you'll grow old waiting for 6max/full ring sngs. Merge is much better for full ring and 6 max SNGs. If you play games other than holdem then Merge generally has more games running, although neither has enough for my liking.
Like everyone else I'm thinking Acr/Wpn will get better and Merge will get worse, so these things may change. You may want to make the move gradually and split your bankroll between the two. If you can put up with the painfully slow players and slow clunky software maybe give the Revolution network a shot.