Rejected it failed aircraft ?
Su-57 was rejected as it failed to prove its capabilities. Hence it is considered a failed aircraft.
By that logic Su 30 must be a super failure... well there was no logic anyway
Use the word wisely...
Their is nothing great about Su-30, only after adding India, French and Israeli sub-systems it became a formidable aircraft.
Su-30 was purchased in 1990s, situation was quite different compared to today.
In 1990s our economy was fragile, we were alone, we didn't have any indigenous alternative, scientific progress was limited. In short we were in bad place.
We didn't choose Su-30 because it was the best, we choose it because we didn't have any alternative. We did the best of our situation.
Today we have alternative, we have AMCA, international manufacturers are offering their state of art planes so why go for sub-standard product.
Design wise it's stealthier and manuverable than Rafale that we are buying.
You are comparing apples to oranges. Rafale has a RCS of about 1-1.25m^2 depending on various sources and Su-57 has a RCS of around 1m^2. With Spectra RCS of Rafale is also significantly further reduced. Lack of stealth is one of the main point why IAF rejected Su-57 so lets not get into an argument who is more stealthier Su-57 of Rafale. Rafale offers much better avionics, radar, EW Suite and engines compared to Su-57.
In modern battlefield EW capabilities are more important than maneuverability and this is where Rafale excels.
What it lack is probably better avionics and engine for now which are in testing phases and developing.
IAF was not impressed with stealth capabilities of the aircraft, engines, projected uptime, avionics, radar and substandard EW capabilities.
Everything that makes a aircraft great, Su-57 lacked; hence a failure.