QFT, currawong. Because of the literal da capo structure, there's less music in the B minor than the G minor (6 pages versus 7-8 if memory serves) even if the first is longer in performance, so that's one reason why I think of the B minor as "easier". What many consider the most difficult passage in the B minor is close to the end of the A sections, with the big arpeggios in the left hand -- but if one redistributes them (similar cases in the coda of Op. 119 #4 and the coda of the last movement of the Second Concerto) it's actually very doable.
You know, after further thought (having played both pieces, along with a whole lot more other Brahms solo works) I suppose both pieces are more or less on the same level. If anyone wants difficult, just go straight to the F minor sonata. Or the Bb concerto. Yikes!

The G minor is (my opinion only) harder; the octaves in the LH require much more technique than is demanded anywhere in the B minor (apart from one place which I'll mention shortly), remember they are semiquavers (and against triplets) and so such fast octaves aren't anywhere in the B minor, remember also that they arise often in the G minor, throughout. They require more control as well, through all dynamic ranges; it requires considerable left hand 'strength'.
The trickiest parts of the B minor rhapsody is at the end of the A sections. Those rolled chords are devilishly difficult; much needed from the fifth finger, but they last only a few bars and so are mastered relatively quickly.
The G minor also has a page marked 'ppp', for notes which aren't played with a 'free hand'; again very good technique is required.
I should think definitely that the G minor is more difficult therefore.

Furthermore from experience, I attempted the G minor first, and had not much luck with the LH octaves (I could play the work, but there was absolutely no musical value in the way I played the 'mezza voce' so I switched to the B minor, learnt that much better, and have performed it succesfully, and over time my octaves have bettered so that I can play the G minor much more convincingly (though I wouldn't perform it, at least not confidently), but I still feel a much greater challenge in playing the G minor, though I've put just as much practise into both (if anything more into the G minor).


G MINOR HARDER!!!


If you play the G minor then you will definitely be able to play the B minor, and certainly it is in no way beyond you.

Janus Sachs - I'm curious, how do you redistribute the notes in the coda of op 119 no 4? I'm playing it now.

I'm not sure where Janus was referring to redistributing the notes in the coda of Op. 119 no. 4, but my guess would be at around m. 248, where I would play the top note of the rolled chord from the LH with the RH instead, since the RH is right there for the next note of the triplet. Other than that, I don't notice any other places where redistribution is helpful.

I had to ask my son what QFT means
It sounds like "more or less on the same level" covers the experiences of posters here. I personally find the G minor easier but it's actually the B minor which I've performed many times.

Morodiene was right -- 15 measures from the end, where the melody is Eb D Eb F Eb D Gb F Gb Ab Gb F, it can all be taken by the right hand. The right hand can also take all the melody notes a little later when it's a single note followed by two octaves, etc. Sorry, I don't have measure numbers.

ah, THAT place... well, if you find it awkward to play but I prefer playing it as written - I find the right hand jumps in the measures before to be much more tricky, but no redistribution is possible here, only hard work!

Yeah, those leaps are killers.