To expand on Lowrider57's comments.
There are distinct styles at play here. Furtwangler in many ways set the standard in the 40's and 50's with a slow and majestic performance. Barenboim in is that mode. On the other side are those who more recently play the symphonies as they believe they were originally played, often at a faster pace and with original phrasings and other techniques and sometimes with traditional instruments. That would be Gardiner and Harnoncourt for example. Klieber was more traditional, but at a much faster pace that Furtwangler, although the sonics on the Klieber are not up to modern standards. Many people think Bohm just got it right, with a good mix of tempo and expression. Although his recordings are from the 70's, the sonics are very good for the time. It is good to recognize these styles in determining what appeals to you.
Fortunately, several of these sets like Barenboim, Gardiner, Haroncourt, are now available for $25 or less so it is pretty easy to get several and compare. Even the Bohm on separate CDs are only about $45. Berenboim's versions with his new West-Eastern Divan Orchestra is also available from HDTracks in 24 bit 96 KHz for people looking for high rez versions.
There are distinct styles at play here. Furtwangler in many ways set the standard in the 40's and 50's with a slow and majestic performance. Barenboim in is that mode. On the other side are those who more recently play the symphonies as they believe they were originally played, often at a faster pace and with original phrasings and other techniques and sometimes with traditional instruments. That would be Gardiner and Harnoncourt for example. Klieber was more traditional, but at a much faster pace that Furtwangler, although the sonics on the Klieber are not up to modern standards. Many people think Bohm just got it right, with a good mix of tempo and expression. Although his recordings are from the 70's, the sonics are very good for the time. It is good to recognize these styles in determining what appeals to you.
Fortunately, several of these sets like Barenboim, Gardiner, Haroncourt, are now available for $25 or less so it is pretty easy to get several and compare. Even the Bohm on separate CDs are only about $45. Berenboim's versions with his new West-Eastern Divan Orchestra is also available from HDTracks in 24 bit 96 KHz for people looking for high rez versions.