Yeah, it's tough to compare JBL vs Infinity.
JBL is pretty much THE standard when it comes to pro-audio, but pretty much a joke in car-audio. For home audio, their studio series has been respectable...well as respectable as it can be for being sold at Best Buy. I think eventually they dropped the studio series and only sold the Northridge series, which is ok. I liked their HTS line back in the day.
Infinity has had some very excellent speakers in the past and on average, comparing all their products vs. all the products JBL has made, I would put them a notch above. For normal consumer affordable gear, their RS line was good and so were the Interludes, Alpha's, and the Beta's. I've not heard any of their new stuff past Beta. I wasn't a fan of the Primus series when it came out. It was also cheaper than the Beta's.
Although I do own both JBL (S36awii, N26awii) and Infinity (Beta 20's, Entra one's, SW-12, and some in-wall and in-ceiling) products, I perfer Infinity. However, even though the s36's are all-weather speakers I bought to put by the pool, they sound real good and I highly recommend them for outdoor applications, so long as you can live with a lack of bass. The N26's I'll never buy again. Their lousy enclosure KILLS the sound quality.