I believe the Delta list has it's valid perks. Like Cubialpha said, it is very small and manageable, which are things that are very nice and convenient if you're just starting out. The nomenclature and pronunciation is based on IPA symbols I think, and all of the English sounds are in fact included and accounted for. Of course, if you judge a Delta English voicebank by the pronunciation of the voice provider, you're going to get very different results if you judge it based on the Japanese voice providers, because they will of course have an accent. The Delta list is quite fine, in my opinion. Very, very manageable.
CZs cvvc list is much more complex as it is, of course, made with a much more specific kind of accent in mind. It's no big deal, either way, it's still pretty simple to make a voicebank using CZs cvvc list, I would believe, since they released a bunch of tutorial videos you can follow.
You can even try making your own list by taking note of the vowels and consonants you see will cater to your usage of English! Research all the possible clusters and end clusters and gliding vowels, etc. But this may be a little advanced for you, not sure!
Look into your options and see which one best fits what you want to do.
I would recommend starting with Delta's lite list because it's very small and it is possible to conveniently hear how the voice and accent will sound like, and since the notation is somewhat based on the IPA notation, and Delta provides a pronunciation guide too, it's pretty universal, in terms of learning how to pronounce what, and how.
Making an English voicebank is really simple, like any other UTAU voicebank, there's more to what reclist you use, it's also how you use the voicebank. So definitely get acquainted with the program and basic usage, if you haven't already!