@evonimos It really depends, do you have or are planing to invest in a decently powered amp, if so get the r70x.
If you plan on sticking to dongles or inbuilt headphone out the srh1440 is a better option.
sure the r70x can be powered off a potato but it will sound "slow" and cluttered even if at the same loudness as on a amp.
Personally I'm not a fan of how AKG tunes their pro line, sure its pretty flat but there is always something off with the treble that makes vocals sound strange. K612 is the usual rec due to pricing over k712.
Although if you are looking at the K7XX I wonder if you are looking for something bass heavy but still have decent mids and tame highs.
I can recomend the ath-a990z if thats the case.
Otherwise just go with the srh1440 if you are looking for a more neutral headphone with decent sub bass.
Edit: Just took a peek at europe pricings for the r70x, unless you can get used srh1440 is better value imo.