Salpingidis was an important member of the team after 2008, he was a regular in the three last tournaments. He arguably was one of our best performers in 2010 at WC and at the Euro 2 years later, he scored 3 goals in that two tournaments (and he gave an assist to Samaras against Germany in the quarter finals). He scored our first World Cup goal ever, he was our first player who scored at both great tournaments. As for the qualification, he scored that single goal at the play-off vs Ukraine, and score again a very important goal against Romania in 2013. He worked usually a lot and took an active part in our defending. From time to time Ninis was given a chance in place of him as a winger but more often than not he failed on important matches. Then the same happened with Fetfatzidis, in the end Salpingidis always secured his place as a starting member in the Ethniki because he turned out to be more reliable and took a greater share in our successes in the last 6 or 7 years.
As for Samaras, he certainly wasnt 24-y-o when he played on loan for some months in Saudi Arabia. Before that move, he achieved great results on club and on national team level too. He played regularly for Celtic, won n-times the Scottish first league, scored several goals in the Champions League. He was in the starting eleven in the Ethniki too, scored important goals (vs Croatia in 2011 or vs Ivory Coast in 2014), and gave great assists, for example in 2009 against Ukraine. He had a share in our first World Cup win ever against Nigeria, then he was a crucial member of the team at Euro 2012 and WC 2014 when the team reached the second round. He excelled against Russia in 2012, then gave an assist and scored the winning goal against IC in 2014 on the vital group stage matches at the last two great tournament. He played more than 80 times for Greece, and was usually solid (no wonder he wasnt replaced practically since 2008).
Fetfatzidis is much more younger than Samaras was in January when he moved to Saudi Arabia, and his achievement with the NT is compared to that of Samaras almost zero. At Euro 2012 he didnt play at all, and wasnt a regular member even in 2014 (he played half an hour against Colombia, and after the mediocre performance of Salpingidis on that occasion he was in the starting XI against Japan but was subbed out after 41 minutes, than perhaps he didnt play at all). He performed a few times fairly well and scored 3 goals on cca 20 matches, but he didnt contribute much to our successes so far. On club level he played for a couple of Serie A teams and was better in Italy than our former saviour Ninis but he never played regularly for any of them if I remember correct. He signed a 3-years contract now, that means he will play in Saudi Arabia until he will be 27 years old. So there is a great difference between his going to Al Ahli and the same move of Samaras (and he was only for a short time there).