The performance between the 3.33GHz and 3.46GHz is minimal. Here are the average 64-bit multi-core benchmark scores using Geekbench 3:
12-core 2.66GHz: 25,500
12-core 2.93GHz: 26,500
12-core 3.33GHz: 30,500
12-core 3.46GHz: 31,500
The 12-core 3.33GHz is most cost effective. However, is you want the absolute fastest, go with the 12-core 3.46GHz.