I considered both the X7-120's and the X8-130's when I was tank shopping last year. Ultimately I chose the smaller-diameter, longer X7 in part because some of the boats I commonly dive from were shortsighted installing tubes that won't hold an 8-incher, whereas of course they all can fit a 7.25" cylinder.
I'm 5'10", but I have short legs and a long torso, so my middle is proportioned like a taller man's. I like the 120's in terms of how high they hold my gear when donning, and the way they trim me out. I hang my SMB from my rear D-ring (off the crotch strap), so it gets sandwiched between my butt and the bottom of the tank - but that lets me know it's there!
I did not think seriously about the X8-119's for the same reasons mentioned above, i.e. if I were to go with the 8" tank anyway, the 130 gives me more gas for about the same weight and profile.
It's all about fit and trim - the Worthingtons are all great tanks. Just be aware of the 8-inch "problem" on some boats.
>*< Fritz