Wow, never? Well, you've quite a lot of playing ahead of you.
My
personal opinions are as follows:
- Road to Montebourg (CMBN US - a classic)
- Scottish Corridor (CMBN UK)
- Road to Nijmegen (CMBN MG - personally my favourite out of the three)
All three very good, huge campaigns which will test your skill as well as stamina. Made by Paper Tiger, who most people will bless and curse in the same statement.
Avoid the following CMBN campaigns:
- Courage & Fortitude (CMBN US, very mixed bag of scenarios)
- Panzers Marsch (CMBN German, designed to be a Defeat for the player - maybe historical, but not fun and therefore not worthy of gaming time investment)
- Kampfgruppe Engel (CMBN German, very hard since you're historically fighting against overwhelming odds)
The following CMFI campaigns are very interesting as well:
- Troina (CMFI US in Sicily, hard but very rewarding)
- Foiling Fustian (CMFI Fallschirmjäger in Sicily, very infantry centric with great scenarios fighting for Primosole Bridge)
- Raging Buffalo (CMFI US during the breakout from Anzio, play this for the great map design alone, it's well worth it and also relatively easy)
The following I can't recommend:
- Conrads Counterattack (CMFI German in Sicily, very very difficult to win, again historical but not fun)
- Fleeting Moment (CMFI Italian / German in Sicily, I simply lost interest midway through)
- The Corridor (CMFI German shortly after Salerno Landings, again very difficult to win, with too short time limits in the scenarios)
- Monte Cassino (CMFI Polish - suitable for masochists

)
I haven't really played any CMRT campaigns, they seem to be quite big again as well. Otherwise I can't really say, some comments on the BFC forum seem to indicate that the German campaign suffers from some very strange / difficult scoring again. So maybe start with the Russian campaign first.