Are we talking long term or short term?
Both, I guess? Just how much you value the reward in whatever way you tend to value them. For context, I play Shoshone a lot so I'm often in a situation where I get to choose between the rewards. I agree that it's often situational. I also tend to look at the rewards mainly for recon units as that's how I get most of my ruins (excepting civs that have spearmen UUs like the Celts).
My personal preference tends to be divided into phases. On Epic speed,
Turns 1-20 I value 1) recon unit upgrade, 2) map as recon unit, 3) territory as this saves a lot on tile purchases 4) free tech, 5) production/gold/culture 6) others. I find that getting a map or scout upgrade early means I can keep my starting unit alive and usually results in finding at least 1 other ruin anyway, so these are the most valuable to me. The xp reward for military units is probably the least valuable IMO - the only one that feels bad to me.
Turns 20-145 I value 1) faith 2) recon unit upgrade 3) tech 4) territory 5) others. My priority during these turns is usually founding a religion. Many of the ruins discovered during this phase are off-shore, so a free tech can potentially mean multiple extra ruins.
Turn 145-200 1) tech 2) territory 3) others. After founding a religion I'm usually trying to grab land so that's most important to me.
Turn 200 onwards 1) recon unit upgrade 2) territory 3) others. Free techs tend not to be available from this point, and my economy is at the point where gold, production etc. is usually a marginal increase. Sometimes a scout that finds a ruin can be upgraded to an explorer though, and being the first civ to be able to cross ocean tiles can be very valuable.