i need two more followers to join the blades - any recommendations ?

Mjoll, and her lackey will follow her anywhere. So, two for the price of one.

Besides, there's no room in Riften for Goodie-Two-Shoes

You can recruit blades? If so is there somekindofa quest progress/reward for doing so or is it just for funsees

The reward is, they will supposedly help you fight dragons. Haven't tested this, and obviously how is that any better from any other follower?
Plus: You can find the wandering followers if you dismiss them because they'll stay at the temple.
Minus: You can also get kicked out of the blades for and not have access to them at all.
Plus: One way to get your wife/hubby away from old flames.