Not all oncidiums have the same flower producing abilities.
Here is one that has 5 flower spikes , over 150 flowers open and 100 more buds; intergeneric Vuyl. Aloha Sparks 'Ruby Eyes'
We all have our preferences, I like a profusion of flowers. But if you want an Oncidium with more than one spike per bulb then I would try a Twinkle (
Orchid of the Week Library: Oncidium Twinkle 'White/Light Pink' ). These routinely produce 2/3 spikes per pb. They are relatively easy to grow and come in white, pink and yellow.