I have both the 88d pro (4U) and TKF Enhanced (4U). As my play style is backcourt doubles and I love smashing, i find that :-
1) Power – 88d pro generates more power. Borrowed a friend’s TKF (3U) and smashes were also not as powerful as 88d pro
2) Control – Because of TKF’s unique handle, find that it absorbs ‘shocks’ more, as such easier to move the shuttle around more accurately, and nets shots were good too. To improved control for 88d pro, I’m using aerobite boost.
3) Speed – TKF – Easier to move around and defends great, but not by much also compared to 88d pro.
I’m using 88d pro as my main and TKF as an off day racket, as its for forgiving. So boils down to your play-style.