If you hold overnight balances, margin savings override commission savings in all but the most transaction intensive strategies. ie For equities, 1000+ transactions per 100k average balance per month. Brokerage commissions across the industry are already scraping the floor. The key is finding a broker where you can realize the best price improvement. Perhaps, through dark pool / complex order book access. Unfortunately, the independent assessment of this is a very esoteric thing and most retail folks just go by feel/perception.
Margin is almost irrelevant when trading naked options, because it is less than your potential loss. What you need to look at is what could be put to you or called from you in a volatile swing.
The result is: It's +- same. I don't have a detailed calculation, because I write down trades after commission deducting, but it's always more or less 2 USD for option spread, no surprise with TradeStation. But please note, that on my TradeStation account I usually do trades with 25+ contracts.
Margin requirements differ between Portfolio margin and RET T account with IB, but the commissions remain the same, well commissions might depend on the volumes traded and the amounts borrowed but not on the REG T/portfolio margin status