Lactic blue cheeses,does such a thing exist?

[linuxboy]

an aggressive strain will help with creaminess?

Yes. Have to balance it with fat and moisture, though.

lactic acid cheese (something with an outcome like Roth Kase's buttermilk blue)

buttermilk blue is not a lactic blue. It's a normal blue cheese.

It's hard to say outright what blue strain will work for you, there are so many variables at play, such as milk, process, lactic starter strains, etc. Try one and see if you like it. If not, move to another one.