It depends on strength of your experience letter ........ first get both letters than let some lay man read NOC description and the letter .......
Also consider the fact ...... if u r directly in a uni or affiliated clg. If affiliated clg, i wont recomend it
If both are equally strong i will opt for marketing .......... bcuz u have more exp in it, although from the wording it seems that all of ur ep in 0,A, & B skills will be counted but no one is 100% sure (excluding Oscar.. he confirmed it through his crystal ball) .......... assuming u have marketing exp in multiple company's ........... u will be hedged ...... even if one exp is not acceptable, other will be
Also, consider CIC cap info and SS data extrapolation at the time of sending ur app.