Stick with Trebizond Archers, especially those trained in... Trebizond! TAs are better because of their lower maintenance cost and are less likely to turn tail in battle. They also make for better generals & governors in backwater provinces.

Because of their Defense rating Bulgarian Brigands may be better suited for skirmishing far in advance of your line but they don't fight as well as TAs. Naturally if the enemy has any sort of light cavalry then such a tactic becomes folly.

Even if TAs were worse Melee fighters than BBs I would still recommend them. The only time you should consider using archers for melee is when you need to chase down an enemy army in full retreat.