Depends on what brand you like. all reciever brands are good in there own way.
Denon, Onkyo and Harmon/Kardon, Pioneer Elite are usually more expensive. But you get good sound out of them and a lot of inputs and output.
I myself have a Sony reciever with 6.1 channel. 100watts each channel from 2002 using 6 Bose double cube and a sony 100watt sub. I find this perfect for my taste.
make sure you get a reciever that does not pass the wattage of your speakers so you have no trouble with putting the volume to the max and blowing your speakers.
The models i would choose from are Yamaha, Denon, Onyko, Harmon/Kardon, Pioneer, Sony.
As the rest said above me,,,,trail and error.....go and test out the recievers at your local best buy or buy and return them.
3Dmark06 12458 o/c stock: 11500
3Dmark03 36861 o/c stock: 32345