Since noone have objected to my statement about 17mm & 24mm = architecture and 90mm = product shots, I presume this is right. I guess the addition is now "45mm = The Dog, avoid it at all cost"
It really comes down to what you want to use it for. The TS-Es can be used in many types of photography, so it is up to the user to decide which one(s) work for him. Tilting to minimize the focal zone can by done handheld, but tilting to maximize the focal zone is usually done on a tripod and checking mutiple spots in the frame with liveview. Shift can done handheld as well.
As others have noted, the TS-E 24 is a good one for landscapes, and you can add a 1.4x TC in a pinch and not degrade the quality too much. Many use tripods for landscape and architectural photography anyway, so the added complexity of tilting and shifting is not much of an additional burden. Same thing with macro and product shots. The 45 is interesting because it is not one that fits in one of those categories. And it falls into the "normal" range where people tend to be prominent subjects. You can imagine tilting for a group shot where the people are not in the same "normal" image plane or tilting to partially correct or stress shots from below/above.
So I guess my recommendation is to choose one that fits with how you intend to use it the most. Getting that right will increase your satifisfaction with using TS-Es.