Kovacevich on Philips budget with Davis is good, as is the Solomon which also used to be available on EMIas part of a box containing all the concertos. The Solomon account is in good mono sound, while the Kovacevich is IIRC in decent analogue sound, but probably remastered nicely by now.
I would also look out for Gilels on an EMI Groc coupled with an excellent account of the 4th with Leopold Ludwig conducting, Gilels is also represented on EMI with the complete pno concertos with Szell and the Cleveland but it is spread over 2 doubles. Gilels was a famed Beethoven interpreter, and recorded the cycle quite a few times and his well regarded incomplete set of LvB sonatas has just been reissued by DG.
Clifford Curzon's account of the 4th and 5th in a Decca Legendary recording is also excellent IMHO. The 4th is mono and the 5th is in stereo, but sound has been remastered very successfully.
Edwin Fischer's mono account with Furtwangler is also excellent, but probably harder to find.
The 5th has probably been recorded by most pianists at some stage so the choice is absolutely massive.
Hope you get a recording you like.
Cheers
Ed