IPS:
- Better color accuracy.
- Energy consumption does not change that much with low or high brightness.
- If you crank up the brightness to max, this screen should be brighter and easier to see under direct sunlight.
- IPS does not have burn-in effect
- IPS has problem with dark or black images.
- Produce better white
AMOLED:
- Lower energy consumption under low brightness but higher energy consumption on high brightness. A pro if you like always on e.g. lock screen clock.
- Color reproduction is more punching and contrast is better but accuracy is not good.
- Theoretically has the lower response time, which better for gaming.
- AMOLED should be darker and harder to see under direct sunlight. You can set AMOLED to high brightness too but I would not do that, since you are risking the burn-in effect to happen.
- AMOLED could have burn in effect.
- AMOLED can go for true black or dark.
- Slightly red tint on pure white.
RAM: you can never have enough RAM, as long as you do not have to pay much more the extra RAM
Check the pros and cons for each display type
Personally, I do not care much about screen type on phones. I pay attention to such stuffs only for TVs and PC/laptop monitors.