TFH is the "sum" of all the other expansions in terms of development, and has more "bells and whistles", but I enjoyed Semper Fi more. A few key elements of diplomacy were lost along the way, such as the effects of Cores, part of what Threat did, and how Neutrality was handled. As an example, now you use spies to raise the Threat of France so you can attack Communist China, instead of using spies to raise the threat of Communist China, which was relatively easy if you had historical claims there (Cores), and more difficult otherwise. The game was a bit more "sandbox" then, rather than being heavily scripted to follow the historical course no matter how stupid that may be under the in-game conditions. On the other hand, giving up all those "bells and whistles" is difficult after you've started to take them for granted.
I'd say, follow the general consensus and play FTH, just be aware that it's both an upgrade and a downgrade to the game.