By Pontus you mean the American Express lounge right? (There is also a public restaurant by Pontus in ARN)

I would suggest so: If you want a meal, or are looking for a bit of quiet, go for Amex. If you just want a drink and are willing to deal with a bit more of a crowd, go for SK.

I have recently visited both and wrote about them in a TR, SK lounge in the middle of this post and Amex lounge at the bottom of this post. Note it's quite long, you have to scroll past the hotel and the dinner, and the breakfast.

...that is all supposing they let you in SK in the first place. LH website says SK lounge for J, SK Gold for SEN, but nothing for *G in Y.