To be completely objective, a variety of lifting tempos is the ideal way to train.
Personally, lifting for the moment is ideal. Generally, I lift at a tempo of about 2 second concentrics and 2-3 second negatives, but if I'm feeling something different I'll go with it. I'll sometimes change tempos during sets, and not just to compensate for fatigue but to respond to energy fluctuations.
I think too many people over-think the whole time under tension principle. I say whatever you feel in the moment is what you should go with. Some days you might feel more explosive and want to go for more of a power approach; some days you'll feel more steady and wanting to control the weight with negatives; some days you might feel like doing a basic up and down kind of tempo. While I don't like to incorporate too many advanced training principles -- as I believe they can get in the way and interfere with what should be simple (K.I.S.S!!!) and productive -- but tempo training is one variable I almost never use anymore. In my early days 2/3 of my training was all-negatives. While it helped me develop good strength on particular lifts, I found it too limiting; I felt like I was in this box and had to train within its confines. I don't like that. Plus, certain lifts don't bode well with negatives in my opinion. Deadlifts are number one on that list. The emphasis on that lift unlike many others is the concentric; I find deadlift negatives to be very awkward and unproductive.