Id do Op90 ANY day of the week. This is cool little movement, much more interesting than K330 imo.

But its also harder (again, imo). So I guess it comes down to which you think you can do the best job of?

Which one do you WANT to play?

I doesn't matter for me, but i prefer the music of the Mozart more. I feel it is more emotional. I think the Beethoven is very dark and subtle.

I WANT to play the one that will be more beneficial to my repertoire

I hate this, i hate when people post saying, what piece should i choose, this one or this one. Don't Let other people choose for you, everyone is going to choose differently, you choose which ever one you want to play.

I like the beethoven one though.

I doesn't matter for me, but i prefer the music of the Mozart more. I feel it is more emotional. I think the Beethoven is very dark and subtle.

Then there's your answer, play the Mozart.  Like jamie-liszt said, YOU decide.

Guys, you don't seem to understand me.
I am not saying you choose for me. I am asking What will be more beneficial to my repertoire ?? And i mean the whole sonata not just the first movement

And please don't talk about difficulty.

Guys, you don't seem to understand me.
I am not saying you choose for me. I am asking What will be more beneficial to my repertoire ?? And i mean the whole sonata not just the first movement

And please don't talk about difficulty.

Pick Beethoven.  (And I adore Mozart!)  Not considering difficulty at all, but considering repertoire.  The Beethoven Sonatas are pretty much the quintessential sonata cycle, and represent the best of Beethoven's output--Mozart's piano sonatas are wonderful, but not his tip-top work.  His 27 piano concertos are what defined that genre. 

So...Do the Beethoven, and save your next foray into Mozart for one of his concertos.  This is perhaps better use of your efforts in building your repertoire.

Have fun!
Teresa

for technical profit of 2 sonatas from your choice
i would go with mozart K330
i think it helps you more with the scale and apeggio that has to be really regular
some of lh apeggi in 3rd movement

i personally chose mozart for my grade 8 because i couldn't stretch 10ths in my left hand for the beethoven. I actually prefered the mozart anyway, not sure why but yeah. The trills on the last page are tricky but u have to practice slowly and then speed up.
beethoven is probably more exciting but seeing as you have a sonata of each im not really sure, i think im going to learn the rest of the mozart sonata too.

I wouldn't say the 3rd mvt is more difficult than the 1st... there are some triplet arpeggios and a few tricky trills, but I can't really see anything that would make this movement much harder technically than the 1st; unlike many other Mozart sonatas it isn't supposed to be very fast after all.

I see benefits in choosing either one of them.

Beethoven's E Minor: Yes, there's that 10th stretch problem in the 2nd theme of the 1st movement, but it's a broken chord. So if you have a good wrist rotation (i.e. using your middle finger almost like a pivot), you can still play it even if your hand can't stretch that wide. For the 2nd movement, the right hand has a lot of voicing work--the outer fingers need to be able to sing and sustain the melodies.

Mozart's K 330: Don't underestimate this little gem. It's too easy to overshadow M.'s Sonatas by his Piano Concertos, which, I'll admit, are awesome masterpieces. But it takes a great deal of skills to bring out all the subtleties in K 330--things change so fast in this Sonata. You need really good articulation and good fingers to do justice all the ornaments. You also need a superb sense of rhythm.

Either one will make you a better musician!

easy solution: pick both.

2 great additions to any rep.   Both are relatively short sonatas.