Slayer (Sniper) VMC bard, vmc rogue, or no vmc?

[Zhentarim]

https://upload.wikimedia.org/wikipedia/en/5/5c/Denise_Rutkowski.jpg

Which of this is best? That is a picture of the character I'm using.

As in, what would be the best combat build?

[Psyren]

I can only speak mechanically as the picture doesn't seem to match your concept at all (at least to me.)

VMC Bard doesn't seem a great match for slayer; it makes you really good at knowledge checks (which they don't particularly use) and it gives you some bardic performances (which are hard to use stealthily.) You're better off leaving that sort of thing for the party loremonkey.

VMC Rogue on the other hand is great. You get trapfinding, evasion and uncanny dodge, freeing up your slayer talent choices for other things. You also end up with full sneak attack progression. This one is definitely worth the feat loss.