To me, Gyokeres is a better striker than Sesko, and I like how Arsenal are fully focused on Gyokeres over Sesko.
Sesko is good on the ball. He's technical, but Gyokeres is the all-around better striker and finisher, he positions better too and has very good box presence, something Arsenal really need.
I don't rate Sesko as much as other people rate him. A player who couldn't score 20 league goals in the Bundesliga might find it difficult to score 20 goals in the EPL. Arsenal needs a point man; they need somebody who can finish off the opportunities presented, and Gyokeres has everything they need. Sporting are being difficult, but I believe Arsenal will get the deal done
It depends on the needs as both have their strengths and weaknesses. Gyokeres is known for his goal-scoring prowess last season, making him a more respected name. Sesko is younger and plays in the Bundesliga, so it's not much different from the Premier League. His future is also expected to be much brighter in England, given the Bundesliga's style of play, which also relies on speed so it will be much easier for him to adapt to the competition in the English Premier League.
Gyokeres plays in the Portuguese league which is perhaps different from the English Premier League and the Bundesliga, so there's some concern that Gyokeres won't be as productive as he was at Sporting. This is just a comparison and may not be entirely accurate, so Arsenal's needs are something to consider.