Hi JKJD,
There will be a difference in sound but you have to decide what you like. There is another very important factor - synergy between different tubes.
A tube may sound very good together with a certain other tube, but another combination may not sound as good. The best source for what works well are other people that have the same amp as yourself and describe their findings.
Another factor that is often overlooked is that the same best sounding tube may not sound as good in a different amp, and conversely, a tube that does not have such a great name may shine in a different amp.
However, some tubes sound very good in many settings, and the Sylvania/Philips and Mullard 6080 are among those tubes.