Because I am not sure what's best. I'd have a vote to find out whether there is a best, but I'm not sure what's the best voting system.

But these things aren't degrees of one another, they're totally different.

Saying "we only ever eat meat, let's try eating an orange and see if we like it before we eat any of this lettuce" doesn't follow any actual logic. You might hate lettuce, you might hate oranges, but there's no specific factor that binds them together.

Also what sort of things would you factor into what you prefer? How important is each of them?

> I mean, if we're going to finally be able to switch it, why not switch to the best option instead of starting with the second worst and switching again later?

Because that kind of lesser-of-two-evils incrementalist attitude is inherent to the first-past-the-post system we have now.