There are a few things to consider when choosing the best cassette ratio for climbing. The first is the terrain you'll be riding on. If you're mostly climbing on steep, mountainous terrain, then you'll want a lower gear ratio to help you make it up those hills. But if you're mostly riding on rolling hills or flat terrain, then a higher gear ratio will be better.
The second thing to consider is your own strength and fitness level. If you're a strong rider who can handle higher gears, then go for it. But if you're not as strong or fit, then it's best to stick with lower gears so you don't overwork yourself.
Finally, think about what kind of bike you have. Mountain bikes typically have cassettes with lower gear ratios, while road bikes usually have higher gear ratios. So if you're not sure what to choose, start by looking at what's available for your specific bike type.
In general, lower gear ratios are better for climbing because they make it easier to pedal up steep hills. But ultimately, the best cassette ratio for climbing depends on your individual needs and preferences. So experiment and see what works best for you!