Goosebumps are hard to find in audio sometimes...its a personal thing. And at the end of the day, all audio systems are a compromise in some form or other...so we all pick our personal choices.
In your case, i would ask a few questions:
1. What equipment do you already have? That makes a big difference here. Both are very capable speakers...imho, they are also very different
2. i owned the Strads but have only auditioned the Tad Ref Ones in Tokyo at one of TAD's main rooms.
3. The Strads can sound beautiful with a mid-powered tube amp...BUT in my own system, i found they woke up (a lot) and maintained their beautiful tonal character (and it is a character)...but with far greater clarity, delineation and most of all propulsive bass power/depth
4. I think with the right amount of power/current, you will the find the TADs a more straight up player more 'linear' sounding if that is the right description. I cannot say how they would react to mid-powered tubes...i suspect not so well? Cannot say.
5. In the end, you can get either speaker to sound great...if you like the SF sound to begin with, you will find it easy to have that sound from most setups...and then if you have a very very high current, powerful amp with good quality source...you will be able to keep that SF voicing...but drive the overall delivery back to the middle of the road in terms of linearity, bass extension/clarity, etc.
That was my own experience with Strads when i had them. Fantastic speaker and if a mint pair of Wilson X1Slamms had not come along, i would still own them today. I have managed to 'customize' the Slamms a little over years of work and remain happy. But the Strads were special.