The H4 would be your best choice.
The other one while having decent specs also has a lot of junk on it that is likely to cause false positives and other anomalies. You will also get better noise specs on the H4, the quality of the circuitry is better. The RT-EVP is a gimmick, made simply to take advantage of the "Ghost Hunter" market and those who will buy something just because it says it's for ghost hunters. The H4 is a general purpose digital recorder intended for those looking for a decent quality digital recorder. It may not be the best available, but is certainly a step up from a voice recorder, and much better than the RT-EVP
The H4 is a great recorder but nothing Id suggest the H2 as the H4 has had reported issues, the H2 is as good quality in recording and has a number of great options including the 280 degree recording. Now the RT-EVP is in no way a Gimmick, yes it was designed specifically for the GH Community but that in no way says its not a worthwhile tool. having the ability to conduct REAL TIME EVP sessions is a HUGH advantage to any paranormal team. Unlike the live listening that many teams refer to as Real Time (which its not, its just amplified audio) the RT-EVP is true real time EVP recording. The quality of recording is as good as the H2 and it does have a number of other feature that some MAY wish to use but ar not essential to the operation of the device. All in all the RT-EVP is the choice when comparing to the H4.
In my opinion. And yes I own the H2, the RT-EVP and even the new H1 I also own an Olympus LS10 which is another high quality recorder I recommend. So I do know a little bit about what Im talking about.