Lancer... would love to use him but the upgrade costs for those scout/light mechs is way too high.  So the only players that use them are whales or beta era players that have already obtained everything that they need and they can now go back and get the "fun" mechs.

Shotguns... this weapon seems like it should have more use in the mid-later game but they are nowhere to be found.  Players just don't bother with them.