I am notsure of other brokers. Personally I do not mind paying 1 or so dollar extra for the kind of service I get. And it is excellent. It is of course what you are looking for. I think that in their so called pro account, if you have 20k or more in your account they can get very close to IB. It all depends on what you are looking for.
IB does charge 4.8$ RT with all fees...that's a good starting point , but I would like to see lower daytrading margin as others offer this... best & have great day, cosmic