Šeško and Viktor Gyökeres can't be compared because we all know that the Sporting CP player is on top of his game and I sure hope he continues with that form and something I said on one of my post about both players is that the one (Gyökeres) with the high number of goals last season can come to the EPL and struggle while the other one (Šeško) with the low number of goals last season can perform at his best in the EPL so we shouldn't say much about these two players, they are good but the problem is the club which is Arsenal. If you're waiting for "Here we go" I feel it at not happen because the pressure of getting any of them can't be seen on paper so let the Gunners continue hoping things would turn out their way.
Say that to the Arsenal board and Arsenal fans. Arteta wanted Šeško while their sporting director Berta prioritize Viktor Gyökeres. The same thing is going on in the fan base, because each fan would prefer one over the other. Well, I dont think Arsenal has a choice here, which ever of them they can get their hands on they should go. They are both very good clinical strikers. Viktor Gyökeres may be poor at scoring aerial balls but he is sure to give you many goals and assist than Šeško who have lesser stats.
For now the fans can only choose who they want but the main thing that would give them joy is for their club to have an attacker like every other club. Look at how busy other clubs are, getting ready to face the challenges that lies ahead with new and reliable players that are joining the team but the Gunners are still stuck at a place.
I won't judge both strikers the way you just did because the EPL has a way of making some of the best players we hype so much to lose his form and when it comes to these two players I wish it doesn't happen that way because I always feel for this second place Arsenal, they should have at least one of those two players to make the squad complete.