I have almost no experience with rts games. In fact, in the past I used to run away from them, but being a huge WWII "fan" and having burned through most of the WWII fps and arcade games, I'm ready for the next step -- exploring rts games -- but what to get? Men of War, Blitzkrieg, Sudden Strike, Faces of War, Soldiers Heroes of WWII, etc. I'm overwhelmed!

Many thanks for your thoughts

All of the sudden strikes and blitzkrieg. Great WW2 rts

Codename: Panzers <3

Sudden Strike is crazy difficult, but oh so satisfying if you actually manage to accomplish something :P Overall however I think Blitzkrieg is the better, and slightly more forgiving game of the two. However neither are 'traditional RTSs'.
The closest to a traditional RTS that I know of where you can actually construct buildings to produce troops is Company of Heroes.
So it's between the Blitzkrieg and CoH series' I think. Blitzkrieg if you want a more authentic experience, and CoH if you want a more over-the-top action experience.

And if you want the most authentic experience of all, then the Close Combat series.

For a more traditional RTS Company of Heroes, especially the first one.

Men of War series is my favorite, I havent tried some of the newer stuff.

The first Sudden Strike was really good too, but difficult.

Company of Heroes was fun, if you can get past building tank factories right on a WWII battlefield. It's the kind of stuff that I don't mind in something like Starcraft, but in a more realistic setting it bothered me to no end.

Sudden Strike Series and Blitzkrieg Series (i personally think Blitzkrieg 1 is the best installment of the Series)
Also Company of Heros 1 with Blitzkrieg Mod (unfortunatly CoH isn t avaiable on GoG yet)
would 100 % rebuy it here

Does that chapter in Empire Earth count?

If you would like a very fun and not too punishing military-type RTS in order to try out the genre, I would highly recommend Army Men RTS. Currently on sale for $2.99

https://www.gog.com/game/army_men_rts

Can't comment on Sudden strike, but Bliztkreig is a good place to start. Especially the first one.

Company of heroes is good too but is far more fast paced, including some missions that are on a timer- my pet hate. (cant get it here anyway)

If you are interested in slowing it down some with turn based, there are many historically accurate WWII games available on gog.

Panzer General 2

Combat Mission beyond overlord, below is a link to this game so you know what you would be getting into.

Only to be considered if you want to get away from rts though.

https://www.youtube.com/watch?v=IOHVnad2GP8

And what would be your recommendations to help someone learn more about the second world war? Hearts of Iron? Is the third one much better than the previous ones?

Order of Battle: World War II is a good pick that will most possibly lead you to search about all relevant WWII operations articles on Wikipedia.

Attentat 1942.

If you're new to RTS games and like a cinematic/intense take I can't recommend Company of Heroes enough. I'm terrible at them and I was able to beat the campaigns and have fun with them.

Just watch the first mission:
https://www.youtube.com/watch?v=6GWp6GmBQGA