Hi Johan, welcome to the forum!
Most of the worthwhile Casino's with WMS have already been mentioned: i do advise you to steer well clear of DrueckGlueck for now, because i just translated a review for them, and encountered loads of ridiculously player-unfriendly terms, especially when you like to play with bonuses.. it may be that they are new, but for now those terms are just insane.
About the ones already mentioned, from personal experience i can say that Vera&John are a good place to play, but offer bad loyalty schemes. However, when you get a match up, it's always worth taking (as they are one of the few that let you play with your own cash first, and withdraw easily when you hit big on that) Also, they have the least amount of WMS titles of all places mentioned, but therefore a lot of Yggdrasil games - most of those are released first @ V&J
Unibet and Maria are great overall, Maria does have a slightly better loyalty scheme, but both can still be improved much (they are working hard on that though, or so i am told) they do have an insane amount of slots, and just like you mentioned in your Leo Vegas review, they also have Yggdrasil games and WMS, and at least from WMS almost the whole collection. If you are creative, you can "make your own loyalty" so i highly recommend them.
MrGreen is an awesome Casino, i.m.o. just because some of the people that work there now, i am convinced your in good hands, but they pretty much always had a stellar reputation. As they recently improved their site, and added WMS, i think they may well become one of my own top 3 favorites, but they have been in the top 10 for quite while now
I did not check the amount of titles yet, but i am quite sure they will add plenty. deffo worth a visit.
Then there's one i didn't see yet, or missed, but it's Redbet. Awesome Casino, which doesn't have the friendliest wagering on bonuses, nevertheless they are very appreciative of loyal players, and also offer great, and plentiful promotions throughout the year, and they probably are one of the very few that have ALL WMS titles that are available for Online play. Highly recommend them.
Then i have been testing Casumo myself recently, but only dabbling, with small deposits. However, just from the sheer positive feedback from fellow meisters, i'd say they are very good to go, and they also have a large amount of WMS (and NovoMatic!) slots. also worth checking if you hadn't already.
Then not from personal experience, as i only made like three small depo's which busted quickly, but mainly from feedback here and other forums i visit, Videoslots seems like an amazing place, with great innovations in the rewards, and they have WMS too, so i think they may be worth a visit. I definitely will check them out, more dedicated, in 2016.
There's plenty more recommendations, but none of those have WMS (yet) so that's for another thread
Figured you wouldn't mind an extensive answer, as you made quite an effort yourself in your LV review