which is a better speaker

Mike, you might want to ask your question on Audiokarma. There are a lot of folks there who have experience with your receiver and both speakers. I will agree with other posters who stated that your receiver should probably be refurbished. 

JBL have a well earned reputation for punchy sound and with the right equipment and setting can make music come alive like no others, IMO. The 120ti have top notch coned speakers. Sorry, don't know much about Pioneer.

JBL is a speaker manufacturer - Pioneer makes everything, not all of it too well.

If it's just between those two I would go JBL. They have what was called back in the day a "west Coast" sound compared to New England based brands.

JBL's were, at a time, the number one monitors for Studio applications.

I find them a bit in your face and a bit nasal at time BUT speakers are SOO subjective. I would think JBL should be easier to find replacement parts or upgrades if need be.

JBL 120ti over those Pioneers any day!

However, those JBLs have tweeter issues.  There is a foam damper behind the diaphragm that in most cases, at this age, are shot.

I would pass on both...

jeebus...what a choice...