Samsung Metro is the better phone if we compare the specifications.
01) Metro XL does have 2MP front camera while Nokia 3310 does not have front camera.
02) Metro XL comes with 2.8 Inch display while Nokia 3310 has 2.4 Inch display.
Both phone comes with standard 1 Year brand warranty but Nokia 3310 comes with replacement warranty.
Yes, you can change the fonts size in Samsung Metro XL.
Yes, Samsung Metro XL does have FM radio.
Yes, Samsung Metro XL does have music player.
Yes, this phone does have a calculator app.