I just started yesterday. My MS-1 is by far the deadliest I have. I did purchase the BT2.
Best game I had was 3 kills and alive at the end with 3!? HP (I have ended with 1 HP). That as with the Leichtetraktor as I ambushed a T2, and finished off 2 starter tanks.
I do have a question though, is there any way to use research points towards something else? I keep accumulating research for my starter tanks and have nothing left to do with it.
Max everything out, and then convert it with gold.