Depends like a lot of things
How far away is the target?
Using a spotting scope for spotting game out west or using it for the 100 yard rifle range back east?
Used at a range on a clear day in mid morning, out on open range a rather less expensive spotting scope can work fine.
Do you have distant shadows or difficult darkness going to dark?
Years ago, I had the optimum chance of checking out a range of scopes. The area suffered a power failure and the building interior, with no interior windows, went to virtual near total darkness. There was a wall with known writing on a banner that could not be seen. The more expensive scopes proved that the writing was clearly seen.
After that, I usually looked at scopes and such in large stores. I'd pick out a shadowy area of the store and compare how that area was seen with the various products. I'd look for a small mark, seen by some and not by others.
At home, I would start to check scopes at dusk, working them over so many minutes, for comparison. We'd pick out a bushy shadowy area across the street, and spot it over an hour. Most scopes, even inexpensive ones, work good at noon on a sunny day. Get in a forest with a heavy canopy at the first break of dawn, in legal time, and the differences are remarkable.
Doing a gauging at home, under the previous conditions, will give you a starting range on what you think you may need.