I know the difference between the two and I realize the one you were modeling is a fedora, I'm just going on gut instinct here. Regardless, I like the flat cap better than the fedora in general for you, not just in this instance. From the outfits you've posted I also think it'll get more use than a fedora.

I take my Homburgers medium rare.

/\  they are taking the piss.

every time.

WWJFKD?

He'd opt for the fedora.

Haha. Christ...

Could you do one with a top hat, Derm??

Although I already knew this, I've arrived at the fact that I, like JFK, am just not a hat guy.  Never have been, outside of an occasional baseball or knit cap.  However, even with this knowledge, I'm moving ahead undeterred with my hat experimenting.  I like the straw fedora and I'm going to keep it.  I'm not a fan of the plaid tweed flat cap.  But this is mainly due to the pattern.  I think I'm going to get a solid color flat cap in gray or maybe tan cord.  That way I won't have the added complication of having to sort of pattern match the hat.  Plus, I think it looks a bit too countryside. 

I should emphasize that these hats will be primarily functional.  I'm not going to wear them every day or when venturing indoors.  These will be hats to employ when conditions call for them - cold blustery days when I'd normally reach for the knit cap but feel the need for something a little smarter, like if I'm wearing a sport coat or my overcoat.  And I'll probably reserve the straw fedora for a warm summer day when the sun's blistering and I'll be out in it for a while and could actually benefit from its protection.  Overall, I just want whatever hat I reach for to suit my outfit.