I have owned and used both of these pedals.
The reason I have prefered the Timeline over the Timefactor is because I could use the Looper + any delay mode.
But if I had the money and the space on my pedalboard, I would use 2 Timefactors because every delay mode in the Timefactor sounds a little bit better than the Timeline’s and the Looper algorithm in the Timefactor is like 100x better than Timeline’s looper.
However, sometimes convenience > sound.
Now I have replaced the Timeline with a Boss DD-500 because, again, I can run delay + looper at the same time. That’s the decision factor for me and for some of my friends who took the same route because of that.
I also have an H9 with most of the Pitchfactor algorithms loaded + Looper.
If you are not going to use the Looper that much, then I will say get the Timefactor. The dual delay, the simpler interface and the pre-post features makes it a more desirable delay pedal.