RE: First kit, 3rd airplane...which one to build..
Any of those would make a great first build. So the choice is more "What you want to fly"
Mid-Star will be similar to your 4*. but due to the smaller size, it will be a lot more responsive.
The Tiger will also be similar to the 4* but more smooth and stable
The SE is sort of a 3-D trainer
And the RV-4 I can't comment on as I have never flown one, but being a GP kit, it should be a nice build.