What is your preferred size for Rooster tails, or any other in-line spinner?

if you're targeting largemouth with a roostertail, go with the biggest one thats available, makes sense to me...

Rooster tails to me are too small for LMB, or at least ones of decent size.  I'd go with a Mepps or Blue Fox, #4 blade or larger.

I would guess 3/8 but I have not personally ever caught a bass of decent size on a rooster tail, just some little ones

My experience is that you can get numbers on an inline spinner, but will mostly be two pounds or less, unless you go to the larger sizes.  Moving up too bigger spinners seem to weed out the dinks but keeps up with some of their effectiveness.

I've got a bunch of the 1/8 oz ones and ive caught trout and bass of all many different sizes.  Nothing over 3 pounds but id look to something else if you're targeting something big.

I wouldn't consider a rooster tail that great of a LMB bait

Mepps Aglia in size #3,#4 or #5.

I make my own in size #4 and they are killer on smallmouth bass.

I use 1/8 or 1/4oz when smallmouth fishing and the same will work for LMB, but as others said it is unusual to catch any of size. However, you will catch pretty much anything that swims. My Dad actually caught a huge carp on one last week, and this past weekend I caught 11 channel cats on the river using a 1/4oz vibric Rooster Tail. None of the cats were real big, but were fun to catch. About a month ago I lost a nice size musky on the same type.