As others have said so well, the matter seems to be more personal choice than anything. I have had both types of sheath but I tend not to carry a ferro rod on the sheath but rather in my pocket, secured to a lanyard by a mini carabiner (Alpkit type) together with my SAK. If I use the rod, it can be easily re-attached and it's kept out of the way and dry all the time.
I don't like any extra weight on my sheath, so that is a key part of my approach. I made myself a knife and a sheath for it with sharpening stone pouch, tinder container and ferro rod loop. That sheath now lives in my spares box as I quickly realised that it was too clunky in the woods: always catching on something and dragging my belt down.
Although it's not a "cool" opinion in some circles, I really like the plastic (?) F1 sheath as a model of efficiency and lightness. It can also be kept clean very easily.
Just my 2d worth.