Honestly think it comes down to personal preference. I researched both before purchasing. Both are very well made and roughly the same price. RubberB, to me, is a bit more aesthetically pleasing, as the raised center section eventually evens out whereas on the E, it stays raised through the end of the strap. The R has 7 holes vs the E's 9 to accommodate the additional ~10mm in length, which I did not need. Also, I like the look of the R's Tang with the slight "tongue" better - just a bit of extra flair.
Again, I don't think you can go wrong with either!