Well first, let's make sure we get the 1.8T Kits, this thread is for the 2.0L so the links will not be correct.
The 1.8T timing belt kits can be found here on the website:
Volkswagen New Beetle 1.8T > Engine > Timing
As far as which kit is best, I feel the Ultimate Plus Kits are the best value and most complete as they include coolant. There are a few components that may or may not be used (camshaft seal, crankshaft seal), but it will not be apparent they need replaced until everything is apart. I've used the Ultimate Plus kits on (2) of my cars this year.
Volkswagen New Beetle 1.8T > Engine > Timing > ES#5954 Tuning Ultimate Plus 1.8T Timing Belt Kit - 06B198479 V2WAF