I’d rank 880, 770 and 990.
All three have too much treble energy, but 880 is most bearable to my young ears (I’m 21). 770 has serious peak around 8-10kHz but can be easily tackled with parametric EQ, while 990 has that treble problem on top of boomy bass.
Yes, 880s do sell at higher price, but you can get the ugly “Chrome” edition ones on eBay for cheaper than 770s I believed (last time I checked for my friend they were selling at 5k Thai bath while 770s are selling for 7k Thai Bath.
Subjectively, 880’s perceived low end is the most clean and extended in my current headphone arsenal (770, 880, HD600, K7XX, M40X).
Of all headphones and earphones I like my ER4SR best, followed by DT880 (for non-trebly songs) and HD600 (for brighter tracks eg metal music and newer, more compressed tracks).