I have Steinberg ur824 and dynaudio dbm50

what should I upgrade first for better mixing results ?

Room

Converters are way down the line. Cap Protons response is actually the correct one....but as per your question..Its def monitors. You could have the best converters in the world, but if you cant hear them accurately whats the point?

romm has been sorted. so what would be an amazing upgrade to the dynaudio dbm50? I was thinking of the genelecs 8050B . need to do mastering also .

You'll have to try them in your room. Dont hold back $$$ in this part of your chain.

From this point on expect less improvement for more money. A monitor that costs you twice as much as the dyns wont be twice as good. Nevertheless you will hear an improvement.
What is your budget?

well I definitely think the monitors can be improved. the DBM50 is the starting range in the dynaudios , so I wouldn't expect them to be of really high end quality. infact after using them for 3 years now , I think they are more on the audiophile side than "PRO" and I can definitely hear them CLIP when I play back mixes at loud volumes , maybe because the amps are just at 50W ?

I was really leaning towards the BM15A , but I would not be able to demo them . with the genelecs I might get to hear the 8050 right here in my room since the dealer here is my friend.

budget is USD 6000.

6000 $ wow!! I envy you right now. Ok I can suggest these:
APS TRINITY
QUESTED V2108
UNITY AUDIO SUPERROCK
Amphion one18
Eve audio sc305+ts108 sub

Dont forget room treatment . About 800 $ diy rockwool is good.
Dont forget something like avantone mixcubes.

unfortunately where I live , most of these brands are not available. I can choose from dynaudio , genelec , eve audio and adam

Eve audio definitely. Very natural sounding monitors. And their sub is very tight

ok. thank you very much for the suggestions.

for that kind of budget ATC all the way, or Geithain!

I picked up a pair of Adam A7x's and don't have a bad thing to say about them, but the room changes how they sound so much which is why I also bought Sonarworks room measurement correction mic and software. Biggest improvement you could make.