I think the Tygon A-60 I bought has Norprene written along the side (which hopefully will wash off), but perhaps Norprene is a somewhat generic descriptor, and the Tygon is still better?As many have stated Tygon is your go to in terms of soft tubing. The other choices you mentioned are garbage.
The big question involving tubing is permeation and zmt and epdm fail miserably.
Back in the day the Tygon variants thar people used were:
Tygon E-1000 - If you want softer tubing and minimal bend radius then choose this.
Tygon R-3400 - Black in color, R-3400 is resistant to ultraviolet light, ozone and weathering, making it ideal for many outdoor applications. Standard inventoried sizes offer sufficient wall thickness to block transmission of all UV light.
I used Norprene tubing sold by Swiftech and didn't like it, the water absorption (by the tubing) was high.
Please don't use soap or oil as previously suggested. If it gets dispersed inside your loop it WILL ruin it and may damage your pump.
With Tygon just use a kettle to boil some water and put the tubing end inside for some minutes, and repeat if necessary.
In any case, as long as it doesn't compromise the potential bend radius too much, I really hope it's soft enough to attach without too much difficulty.
BTW, if a bend radius is too small, will it kink immediately, or otherwise signal that I need to make an adjustment? If it just slowly kinks until finally stopping the flow two weeks later, I'll have no idea there's a problem, at least not when I'm actually able to work around it smoothly.