Which tier IX to spend credits on?

Ectar:   M103 is an awesome tank, as it the Jagdtiger and Foch.  Personally I'd take the E half hundred ramwagen.  All of them lead to great tier X tanks and they each play pretty differently.   M103 - Is a good supporter/frontliner it trains you well for E5. The top gun if you decide to go for it is the same as the E5 so you'll know what it's capable of. Jagdtiger - Is all about sitting back and shooting what your team spot. Don't forget to protect the lower glacis plate as people will aim for it. Don't forget your repair kit/extinguisher combo. Foch - Can be played as an assault gun, it's a good TD to play aggressive in. - Watching Circonflexes play this tank recently really showed what it's capable of. T54E1 - You really need to make the shots count. I'm playing it now and it's a bit of a shot magnet as people sometimes think you're a T57.  Don't be caught on the front lines with this as your main job is finishing tanks off, or bringing people down for a team mate to finish them. E50 - Ram, ram ram ram and ram again.  This tank can be played as a mobile sniper or as a back up battering ram. It has outstanding accuracy however it sadly doesn't have the gun depression to rival other mediums but you'll soon adapt and learn new places to shoot front.