Hands down the INDY Maxx Aluminum Block and like someone else said you can not go wrong with Todd Marsh and would not be afraid to use others on the board that's a full time business.
Another thing that might come into play is who now has the blocks in stock,it matters not so much as who's is best if you can not get it!

PS I have owned 7-8 Indy Maxx blocks both RB & LD and have never had but one problem out of any of them.And that was when #5 rod broke & took out #6 rod also at 7400 RPM... long story short it had holes in both sides of the block.A fellow Moparts member told me of a place in Atlanta and they repaired it to where if you did not know where to look at it you could not tell it had been repaired.It also had to have 3 sleeves put in it from the damage,but it was once again in like new condition.Try doing that with a cast block.