You will get a lot of answers on this one. I assume you are asking about an entire radio system.
There are a lot of good ones out there. From my own experience I would stick some with the companies that have been around awhile.
FUTABA
HITEC
AIRTRONICS
JR

As for number of channels a 4 channel system will work on most planes, if you think you would later like to go with retracts or flaps a 5 or 6 channel or more is needed. Check Tower Hobbies to see a good selection of whats out there. If you are looking for a receiver only HITEC make a couple of good ones, stay with the 7 or more channel receivers.

Dale Jenkins
Southern Eagle Squadron
Leesburg FL