It depends on T/S parameters of these drivers and your goal and the design of your cabinet.
It will be helpful for others to give their opinion if you can put all your information here like T/S parameters of these two drivers, your cabinet design, dimensions.
And also please explain what you mean by better bass. What is your goal? What is better bass to you? Is it thump, attack, accuracy, depth, tightness, weight, speed.
If you ask these question to yourself as well, you will come closer to a conclusion.
I am nobody in cabinet speakers and that too in bass section, but I surely know detail in question can bring detail in answers.
In other words I want to understand which one can handle more power at low frequencies.
The specifications does not mention power rating, if someone have actually tried these two drivers, please share your listening experiences.
If you are not asking many question, then let me ask you. I will learn something about cabinet speakers by talking with you.
What are the SPLs of other drivers that you will be using for your 3 way speaker? What is your target SPL? What is you think your limit of dimension for your speaker, as that can probably eliminate 8" woofer at the very beginning. Are you going to use two woofers to increase SPL in lower frequencies?
Xmax of 8" and SPL curve of 6.5" is missing which could have been quite helpful to choose.
Actual SPL for the 8" in for frequency below 100 Hz is quite lower than claimed 92.3 and dropping fast.
Why you want 900 Hz as low pass point?
If my other drivers have SPL around 83 dB, I would have gone for the 8", if they are more than 87, I would have gone for 6.5" X 2.
The amplifier used for this is giving lots of loose connection problems now. There are many wires connecting to lots of PCBs. I shifted house and moved the amp many times in last few months. So instead of fixing it every time, I decided rebuild it and minimize wires. I planned to make just 2 PCBs, one for all amplifiers and 2nd for all power supplies, and reuse the existing active filter pcb with minumum changes. To reduce complexity I plan to remove subwoofer section from the amp and remove high pass section of 70-900Hz bandpass from active filter to make it 900Hz low pass and remove all components of 114Hz lowpass.
I decided 900Hz because I already have a active filter with this value.
My existing speakers will not produce much bass without subwoofer, because mid-woofer enclosure is sealed and have very less volume and was not at all designed to produce lower frequencies. So I plan to make a new enclosure and checking options for replacing woofer.
I don't care about SPL, because this is a active setup, I can easily adjust volumes of each amplifier to match SPL of all drivers. Or worst case, I can adjust the gain of output opamp of active filter by just changing a resistor if SPL is too low for any driver.