A big thing to consider is what you are cutting. Here, we run a Stihl 362 with a 20” bar as our first step up from the top handle. The 362 is also the “small” saw for crane work. Our next step above that is the 461 with a 25”, and then a 661 with a 36”. We find that the 20” bar is enough for 85% of the cuts that a 16” on a 201T won’t handle, if we need bigger we send bigger.
If you’re cutting softwoods, you might run a 25” on a 362, or run a 261 with a 20” and find it’s plenty for you. Around here, in our hardwoods, we need more power than that.