I had both, but gave the Bachelor to a friend who seemed to enjoy it.

For me the only benefit the Bachelor has over the Serpent is that the glass section can be replaced. Serpent has much better airflow for my style of vaping, I found the flavor significantly better and just an all around smoother vape.

Bachelor is really a good tank, if you like the airflow from a Subtank Mini. It's basically the same, with basically the same flavor as from the STM RBA section.

Serpent with a clapton coil, for me, even wins in flavor when compared to a Kayfun.
But every vape style is different. You may love the Bachelor more, nobody knows until you try.