I plan to buy couple games from rebellion sale and I tend to buy two full priced games along when I buy from sales. I'm currently in need of turn based strategy fix and Fantasy Wars or Strategic Command: European Theater seem best choises from my wishlist.
I tend to prefer grand strategy over one front or scenario based campaign games so SC:E seem better choise but it seem simplistic on economy side as I also like to build infrastructure to help my war machine. Does game have any sort of diplomacy or is it historical on that front?
Mind I did like Fantasy General (and all other General series games) alot back in the day (FW tries to be spiritual successor does it not) but I tended to lose interest after few playthrus as battles became predictable. Does FW offer longer campaign and/or bigger/grander battles to offer more replay value (trying different strategies against same opponent with same army composition, formation and tactics does not offer replay value to me)?
Which one should I buy? It's shame GOG has not managed to get more turn based grand strategy games to it's catalog as those two are pretty much what I'm left to choose from (Generals series needs rest of the series and series sale as I own or have owned most of the games at some point).
I'll be away this weekend so decision will have to wait till monday (I probably won't even be able to check suggestions before then) so suggest away. Thanks in advance!

Light on economy? Well, it is no Hearts of Iron....it is a wargame, not a a strategy game.
You are focused on the movement of troops and battles, not economic infrastructure. More like a field marshal or say Hitler than Albert Speer.
The economy in SCET is about making sure you occupy hexes which contain cities, harbours, mines, oilfields, which provide Production points. You can then choose what you are going to do with them, keep them, use them for urgent strategic transportation, research, manufacturing of units.
It is possible to not just capture them but also to bomb them to reduce their capacity/income for the enemy.
It's a very good strategic theatre wargame.

Thanks both of you for your answers, I had wished for bit more and more extensive aswers but they're enough to help me choose. I'd mark both as solutions if I could but as I have to choose I chose mystrals answer as he convinced me not to choose Fantasy Wars at this time. Ended up buying 4 games in the end, 2 from the promo and 2 full price.
Thanks again for advice. Neither ended up being quite what I was looking for but SC:ET has to do for now. Hopefully we'll see more TBS games at GOG in future.