Liquid Antimatter's win rate is really low, but not as low as some of the others. Unfortunately, efficiency doesn't equal a high win rate. You'll need upped decks for a good win rate. Efficiency takes into account both win rate and the time it takes to win.
LA isn't the most efficient unupped deck because it wins a lot, though it does win more than other unupped decks. It's the most efficient because it wins and loses really easily/fast, so you can move on to the next game as soon as you know you'll lose. While that sounds bad, the payout from even one successful spin outweighs the massive loss rate. If you read the False Gods Efficiency Index thread, here, (
http://elementscommunity.org/forum/index.php/topic,25609.msg349340#msg349340) you'll be able to know what to skip.
Also, the Money Management (
http://elementscommunity.org/forum/index.php/topic,27551.0.html) thread in Newbie tutorials is a must read, if you haven't seen that already.
Edit: Also, as YCH says- you've looked at the strategy guide, right?