I don't trade that much now but the more I do the more I'm concerned about costs.
It really depends upon how frequently you trade and what you trade.
There are very very cheap stock-only brokerages; anecdotally I believe they do not get good executions, but that can be overcome by only placing limit orders.
As far as I am concerned, if you place 50 trades a year or less, it hardly matters if you are paying $5 or $10 a trade.
I trade lots of options and probably do 8-30 trades a day, would like to be around 5-15. Options trades typically have a base charge of $5 or $7 or $10 (whatever your brokerage charges for a stock trade) PLUS some amount per contract. That amount can be 75 cents or $1.50 and THAT per-contract creates costs. IF you trade opts a lot.
If all you do is to trade stocks a few dozen times a year, IMO it is not important what your comms are. The caveat I would offer, though, is if when you trade ONE stock you very carefully scale in by buying 200-300-100-400 shs at different times and different prices to get to 1000 shares, that of course is four trades, not one trade. Same on the sell side.
In terms of “vanilla” brokerages, a friend of mine has a Schwab account and I was surprised to find their commissions are VERY competitive. Including options. They used to NOT be. I am where I am because there is no comparison to the options analytics available @ TOS. None, not even close. And they are very competitive comm wise. They also have access to futures which I do not trade but I *DO* trade some etfs a lot that mimic futures, so having access to futures info is valuable to me. Another brokerage I have used which is a superb brokerage with very low costs and top notch answer-on-first-ring cust svce is Lightspeed. Their claim to fame is their front end, not for analytics but for speed of execution. Their front end is a flaming Ferrari, it’s potentially lethal with how fast it is and the number of ways to act it has.
I should say that the dead nuts cheapest brokerage is Interactive Brokers, but their cust svce is ummmm, primitive in its way, and its front end takes some getting used to. >>BUT<< they directly pay the customer what most brokerages receive for order flow and for providing liquidity to the market. I have done plenty of trades in my IB account where the commission is...38 cents. $1.26. $2.13. Crazy. I have done trades there where I have produced negative commissions, actually getting paid to make a trade. You can download a fake money front end to try it out.