Welcome to ECF!!
My current Mod becomes my back-up when I get a new Mod.
I don't think that a juice tastes the same to everybody. Different systems, different draw, different power settings, just different. But, for me, I like the "samplers" that many on-line vendors have. I get to try more flavors on my system, my draw, my power settings, and my taste buds.
I have a spreadsheet for my juices and I rate them. When I find a top-rating flavor, I know I can go back to it.
As to tanks, I have many. I have a tank with higher nic to go with my morning coffee. Currently it is a chocolate mint. In my stand I have 5 others that are my daytime vapes. Since I lose the taste after a couple of hours, I change toppers a lot. Then, I have one tank and two drippers with a step-down nic level for relaxing in the evening. I naturally vape more and I don't want to overdose on nic. The drippers stay at home and I use those more. The night time tank is for going out to a vaping friends house. I just tend to vape more.
So, yes, having more than one topper helps make the hobby fun. I always thought that cigs were boring. Vaping is not.
Have fun!!