I was looking at some AVRs from S&V magazine. This was before they stopped doing measurements.
But looking at some 4 ohm/2Ch power measurements, which is probably most indicative of true power performance, it looks like the Yamaha RX-A2000 series might be the most "cost-effective" in terms of dollar per watt when looking at Denon, Marantz, Yamaha, and Anthem. The $6000 Arcam is definitely the LEAST cost-effective.
But the bottom line might be that ANY of these AVRs, ranging from 173W to almost 300W, could probably power 99% of the systems in most rooms that are 18ft x 20ft or smaller.
Yamaha RX-A3000 series $2,000 294W x 2Ch 4 ohms
Denon X7200 $3000 266W x 2Ch 4 ohms
Yamaha RX-A2000 series $1600 260W x 2Ch 4 ohms
Arcam AVR850 $6000 249W x 2Ch 4 ohms
Anthem MRX 1120 $3500 243W x 2Ch 4 ohms
Denon X4000 series $1700 240W x 2Ch 4 ohms
Marantz SR7000 series $2,200 232W x 2Ch 4 ohms
Denon X3000 series $1200 177W x 2Ch 4 ohms
Yamaha RX-A1000 series $1200 173W x 2Ch 4 ohms