I'm using a large Aq neo diffuser on my 118G. It creates the finest mist and with decent flow gets to every area of my tank. The problem for me, personally, is that I'm not a fan of the sprite/lemonade look. If that sprite look doesn't bother you then I'd highly recommend this diffuser.
I'm looking for an inline diffuser for 16/22mm that doesn't require a specific/high pressure as my co2 regulator isn't pressure adjustable.