場合によるみたいです。
gwlim氏( https://github.com/gwlim/mips24k-ar71xx-lede-patch の著者)は
https://forum.lede-project.org/t/qualcomm-fast-path-for-lede/4582/276 で、
>you will know all 3 components are required to achieve Gigabit NAT for MIPS74kc AR9344 and above.
と言っています。

一方、dissent1氏( https://github.com/lede-project/source/pull/1269 の著者)は
https://forum.lede-project.org/t/qualcomm-fast-path-for-lede/4582/294 で、
>For k4.9. You should pick only kmod-fast-classifier under kernel modules - network support in menuconfig.
https://forum.lede-project.org/t/qualcomm-fast-path-for-lede/4582/378 で、
>I've made a clean commit to form a pull request. Could you guys test it, I haven't found any problem myself.
>You can choose either fast-classifier (recommended) or sfe-cm. Both shouldn't be loaded at once.
>If both are loaded then sfe-cm takes the lead and fast-classifier (more advanced) doesn't do anythithing.
と言っています。

なので、gwlim氏のパッチを使用する場合は3つ全てをインストール、
dissent1氏のパッチを使用する場合はkmod-fast-classifierを選択するのが無難っぽいです。
何か間違いがあれば指摘をお願いします。