The game is changed, changed utterly, since Cata. There are issues you are not taking into account.
PvP servers have been abolished. PvP in general has been encouraged to decline, until participation is much less than it was.
If you want to PvP in the world, you switch on PvP Mode, and then you are mixed with people from a whole lot of realms who are also in PvP Mode, but they are not people you will ever see again. So the mix of H:A depends on who’s logged on across Europe. (And Horde are always in a large majority in PvP Mode.)
So balanced realms serve no purpose anymore. As the game is now, it is frankly stupid to want to be on one. That balance, that dynamic that can still be there in Classic is gone from Retail. All benefits of PvP realms are gone.
So not being stupid - or at least not being that stupid - most people having experienced the result of these changes have voted with their feet and settled on completely unbalanced realms where they are in a crazy majority.
I’m personally sore about this. During a time when they were having capacity problems a couple of expansions ago, Blizzard gave free transfers for Horde to my Alliance realm, making it balanced-ish. It has been going downhill ever since. 
Blizzard have removed the info we used to be able to get about how many characters per realm, but this site is maybe a proxy for relative size and balance:
Personally, if you have no specific preference, I’d go Horde. There is no doubt that it is the more active faction, by a lot, at the moment.
Personally, I’d say Draenor for Horde or Silvermoon for Alliance, unless you have a reason to choose otherwise. Some English realms are unofficially colonized by other languages, some of whom cause friction, but you will find Swedish guilds on any of the large realms, and they tend to be very nice. You can also check out the Realm forums of the Looking for Players forums.
If you want to look beyond Draenor among the large Horde realms, although I don’t know any but Draenor myself, Kazzak has a rep of having some less than polite segments, and Twisting Nether and Burning Legion have significiant non-English-language (and non-Swedish) contingents.
But the only way to size up a realm for youself is to make a character, run to Orgrimmar, watch Trade for a bit (if you can keep up with the boost spam scrolling so fast) and try to get a sense by talking to the people there.
Beyond guilds, you can also join Communities. These are cross-realm groupings that are otherwise like guilds, and they are not exclusive; you can join as many as you like, while still in a guild. Have a look here: https://eu.forums.blizzard.com/en/wow/search?q=swedish%20category%3A231
I wish you luck in your search!
