That's how I would like them to look. I love those statues. They look like a mix of the cartoon and original movie with the gritty tough edge of the comics.
I've always thought it would be cool if they expanded on the origin story not by changing anything, but by spending more time developing their training. And play up the fact that ninja are essential the special ops concept of feudal Japan. Where did Splinter get their weapons? Why, I'd say he found somewhere, broke in, and stole them.
Where do they get computers, TVs, etc? I'd expect garbage that Donatello repairs, but they're wired into the city and stealing electricity, stealing cable. If they tangled with a robber, they might take his wallet and that's how they pay for getting food delivered.
Really explore their training with the old classic kung fu movie style scenes where Splinter is just plain grueling and vicious with their training, but then a completely different side of him when they aren't training and he's their father figure.
A plot that revolves more around training, preparing, even a few practice "missions" top side, the first time they fight, hell the first time one of them kills someone. Because the first story would be great to be, at its core, a revenge storyline. Training the turtles to avenge Splinter's master by doing what ninjas are trained for: Assassinate Oroku Saki. Maybe no Casey in the first movie, maybe not even April until the second, though that almost seems blasphemous as she offers that connection to the city and expands on just what it is they feel there is for them to fight for beyond revenge.
I always thought there was a lot of material there to do a lot of character development. Splinter should be portrayed with a dark side and personal inner conflict that he's basically raising these children, now teenagers, to be assassins to get revenge on Saki.
Leo being his strongest student, but father/son disagreements as Leo has more of a bushido view on things rather than Leo being the teacher's pet stereotype. Of course, Leo honors his father's wishes, and he's committed to what they are training to do, but he might have the most reservations about their methods and how they should approach things.
I definitely think it should be a team movie, though. No more focusing on the Raph/Leo friction. Raph has been the "star" of the movies too long and Leo the foil to him, leaving Mike and Donnie with less screen time development.
I always thought the notion of going top side and actually making a difference in the city would be interesting for Raph or Mikey to convince the others they could fight crime and use a Batman comic as his inspiration.
And for the love of pizza, Leonardo needs to cut some people. Seriously, the PG ratings have always kept him tame and never able to use his blades. Let him and Raph both use their weapons effectively, not just for show amidst their kicks.
Just some random thoughts I've had over the years.
As for the question of how they should be made, I'd go for either animatronic suits mixed with CG or straight CG like Planet of the Apes or LotR Gollum. Imagine the fights scenes they could come up with if they had a group like Jackie Chan Stunt Team choreographing fight sequences and it was then CG'd over the actual martial arts performances.