sngs suck (yes, ill repeat that sngs suck)
nL ring is easily beatable at <200nl just by set hunting and making opps make horrible calls
Limit is more about making good decisions repetitivly.
While NL player has the satisfaction of being up say 10 buy ins limit is about the long run but it is just a profitable imo.
Ive played 5/10lhe and upto 200nl and turned over similar profits at both.
It really does depend on what you like. Eventually though, play both.