I really don't know why people love massive so much when there is other pretty good vst and it is free.I dedicated myself on finding other ways to make basslines and i must say that TAL-Elek7ro is awesome and it is free.It is so simple to use yet so effective.However dont expect to make basslines you hear using just synthesis without any further automation and processing!!
It's true that TAL - Elek7ro (as well as NoiseMaker) are both excellent, free synths.
However, Massive is a beast all its own. It's loved by many because once you get the hang of it by learning about the interface and the tons of routing/signal chaining/step sequence/ automating etc. possibilities (I found the manual and YouTube to be the best teachers), there is virtually unlimited potential for creation any kind of sound. To add, everything (seriously, everything) can be routed, automated, etc. And the ability to freely move between a pair of wave tables generates unique sound movements, especially with bass noise.
I often will go through the presets and when I find a unique sound, I'll analyze it to see how they're achieving that sound (i.e. what's being routed/sidechained to what, etc). I learn something new each time.
Basically, Massive offers unlimited flexibility in terms of a means to create sounds whether its leads, bass, pads, plucks, FX or just weird shit in general. Most importantly, it has its own sonic character.
I had buyers' remorse after first purchasing it, but once I took the time to learn it, my remorse quickly disappeared.
Cheers.