I've noticed this has been a reoccouring topic over at Juiced Muscle lately. On paper, they have a very similar half life. Cyp is slightly longer, but in the real world, I don't think you are going to see a difference. I do believe that the speed at which a drug releases can slightly change the effect and for this reason, I do like to rotate between test esters. If I used cyp on the last cycle, I may use test E or Sust on the next. This is just my bro science theory though and I doubt that my development would look much different if I had used one form of test through every off season I've been in. So personally, assuming your cyp and test e are both from a high quality brand like Geneza, I would opt for either and if one is cheaper, I would go with that! 

As I mentioned on JM about this topic, there is one more thing I would like to keep in mind. A lot of the higher quality UGL's are slightly over dosing their test. I have seen a number of lab reports on GP that show higher doses than the label claim. Test E is a lot easier to brew and can more easily be stable at higher Mg's. Cyp is a little tougher to keep dissolved in oil. The more hormone added, the harder it is to dissolve. Thats why pharm grade cyp is always at 200mg/ml. GP has a label claim at 250mg but I have seen tests showing 270mg. This is a lot of hormone per cc but it can be done with a good working knowledge of gear. On the other hand, Test E holds better at higher Mg's, and I have seen lab reports come back as high as 300mg's per ML. So there is a chance you will get more bang for your buck with Test E when using a UGL, as it is easier to over dose and adding 50mg to each shot will certainly make a big difference in the long run. Just something to keep in mind ;)