The differences within the broader English/Balkan category are not always so pronounced as the differences within some other categories, probably because the similar or same latakia somewhat subordinates what might otherwise be the points of difference.
I don't want to overstate that, of course. Each English/Balkan blend is discernibly itself, discernibly distinct. But some of us have found that latakia accumulates in our pipe smoking experience over many years until many latakia blends sort of run together for us. (This does not happen with Virginias, for instance; also, it does not happen to everybody.)
My point for you is just that, if you really like English right now, then you'll probably like any highly rated English just fine, and you may not find a profound world of difference between Balkan Sasieni and Magnum Opus.
(Again, I don't want to overstate that -- you'll certainly taste differences -- but those differences sound more pronounced in writing than they taste in experience.)
In other words, you can't go wrong either way.
But to answer your question, just in case my taste happens to be the same as yours (which is unlikely), I remember liking Magnum Opus more than Balkan Sasieni.