It's actually PAR that determines how 'good' or efficient a bulb is. But I wont go into that because it's not commonly labelled on boxes...
Lumens are what most people go on, though it is a measurement of brightness and as you said plants don't have eyes. The approximate Lumens per square foot of growing area is about 1000+ Lumens psft at the absolute least (if memory serves).
What spectra are they both? you want 6500k colour temperature for Veg and 2400k for Flower but you can use both temps for both cycles mixed spectrums work very well. As for the wattage, the more the merrier, but your going to want more than 1 x 26w bulb and 1 x 50w bulb.
Oh and make sure your reading the "Actual Watts" not the "Equivalent Watts".