For a 4x8, shoot for 1300 watts of Samsungs, about 40W/sqft. Design the layout to emphasize the walls and corners, with the boards or strips snugged up against them. The middle will take care of itself.
Drivers are pretty uniform in their own cost/W, so you could have more small ones or fewer large ones - price per watt will be similar. It'll be more important to match voltages.
I run exclusively 3000K in the bloom room and 4000K in veg. My own opinion is that spectrum is wayyyyy down on the list of important factors. Many other people use a blend. I find the reddish tone from the 3000K boards to be irritating in pics, but it's not noticeable in person. The 4000K spectrum looks white both ways.
And Arrow has better prices.
Vendor Cost for Samsung SI-B8V261560WW