Hi could anyone please tell me which radio reciever I should get if I want to be able to recieve as many frequencies as possible. Thanks!

This makes no sense.

Agreed.

Radio Shack has several scanners that would receive many signals.

I have an old pre narrow band AM receiver that was always good at picking up a lot of frequencies.

The question is.....
Are you asking about an AM or FM or a 2.4ghz radio ?
AM 6 channels
FM 29 channels
2.4ghz I have no idea because it's all automatic
The brand is important as some conflicts exist.

In the USA the RC surface frequencies that do not require an Amateur Radio (ham) license:

27MHz band has 6 channels, numbered 1 to 6: 26.995 through 27.255MHz.
75MHz band has 30 channels, numbered from 61 to 90: 75.41 through 75.99MHz.
Both the 27 and 75MHz bands can be either AM or FM.

Not sure about 2.4GHz band. Seem to remember Spektrum claiming 80 channels, but 2 are used for a model?