Imran, naming bread and viennoiserie narrows it usefully.
An OTG is fine for cakes and cookies and the weakest of the three for bread - limited bottom heat, poor recovery when you open the door, not much mass to hold temperature. A convection oven gives even heat and better recovery, the most versatile single purchase for a mixed home operation... though the fan can be aggressive on delicate lamination unless you can control it. A deck oven with proper stone and independent top and bottom heat is what bread genuinely wants, and it's a significant step up in cost, footprint and power. A small-commercial decision, not a home one, for most people.
Vikram's advice is the right FIRST move. Add mass to what you already have, costs very little, and it isolates whether your problem is the oven or the technique.
If you're heading toward selling bread, the honest sequencing: prove demand on your current setup with a stone → convection as the first real upgrade → deck only when order volume rather than quality is the constraint. Buying a deck oven before demand exists is one of the more expensive mistakes we see.
