I'm with IB. I pay $120/year for 120 trades, but that includes options and all trades over that are essentially $1. I'm not all that active but there are a few things that keep me there.
1, their customer service has always been excellent
2, their platform keeps getting better. Now you can do everything through the account Managment login
3, 1.67% margin interest! I loaned myself money to get a car and paid it down with options premiums (a little, hah). That is a lot cheaper than a credit union loan. I hate credit, but that is some cheap money.