Depends on your criteria.
Målilla MK (Dackarna parent organisation) have a very organisation for arranging GP:s. But it is very in the middle of nowhere.
Västervik have a very good track, but they claim that their pit area is too small for SGP.
Sannahed is a good track, but Sannahed is a bit off (30 km south of Örebro)
Eskilstuna has very good facilities (except parking) but track is a bit meh at the moment. Located about 12 km outside town but would probably be bus transfer available.
IMO those are tracks that a GP maybe could be held at.
Västervik are fairly close the city. Norrköping and Motala are in the city or in the outskirts of the city. Hallstatvik is also central in the municipality
in which they are based. Gislaved is also quite close to the town.