I'll chime in here. I went from 2150s to 3677s to get the speakers lower in my baffle wall as I installed the 2150s a tad to high and the first row was off axis. I wasn't redoing that wall..lol. Do I get sad when I see them in Jeremy's wall.. yes I do!
I went from 3677s to htm-12s because I found i sat in the back row all the time and liked the 40 degree viewing angle vs the 53 degree. My mains were spaced for the front row. Front row sounded huge and immersive 2nd row didn't as they were too close for that row and sound stage collapsed. I needed to flank the screen to get them spread out and the 3677 wouldn't fit. Now I get the sound i had in the front in the back row too as I'm spread 45-50 degrees now in the back row.
All of those speakers are awesome. There are some differences between them but at that level your counting hairs as to which is better and I'd say real performance comes down to setup and room acoustics.
JBL vs QSC .. Anyone that's been to film tech has noticed QSC is king. The do however like JBL especially the 4722 of course some JBLs they dislike.. heck many don't like the 3677. The 4722s rival is of course the 2150. both are designed for rooms that are not Home theater size. The 2150 wave guide is very similar to what's used in the Titan so take that for what you will. Heck all of these are designed for screening rooms and larger.
These QSC speakers were designed by Paul Hales. You may have seen him on Home Theater Geeks episodes talking about room acoustics etc. He now has left QSC and started this company. http://proaudiotechnology.com/
JBL and QSC both know how to design good speakers.
Now on to personal tests. Love 3677, i've also owned the 8330a, 8340a and both are boat anchors and IMO the volt 10lx and so many other speaker are much cleaner and not harsh like the JBL pro surrounds I've owned. I've also talked to a few 8350 owners who weren't satisfied but know some that do like them. It's personal taste.
4722... I have heard some like the 3677 better some the 4722 better, but these are never in the same room so it's hard to make a decision based on that. I've heard some say they are the smoothest ever then next they're swapping the CD to make it smoother and later say it was a tad harsh. A good buddy had modded 4722s (Be mod) and installed his friends 3677s. He liked the 3677s better. That got him looking to change and after lots of research into off axis response and the new JBL M2 waveguide technology now has JBL 708s. He feels they have better detail and are smoother than the modded 4722s and believe it or not no mid bass was lost and they sound every bit as huge. His room is treated including some combo panels so he has the perfect space to use awesome off axis. Again, these are opinions so take them for what you will. I also sold 2 2150s to a guy with 3678s. He felt the 2150s were far superior. Again his opinion but remember price doesn't guarantee performance.
IMO they are all good if they meet your needs and can be integrated into your room in a way that uses their strong points.
Now my opinion on selecting speakers.. not that it matters..
If you want the best without spending a crazy amount. JBL 708. The technology in the new waveguide is pretty awesome and the waveguide hold several patents. That and a properly setup room will be hard to beat. Along with the use of good reflections adding to the sound power you'll be able to hit clean reference in a good size HT. Of course they won't go much beyond that like some of these other options so it depends on goals.
If budget and/or DIY is your thing HTM-12 , Titans (2150 guide) etc would be my pick. Great responses with great off axis. I'd personally pick this option over everything but maybe the 708s if I wasn't too cheap. I mean the Titan has many similarities to the 2150 and it's a great price and the htm-12 I own and I have zero regrets as I can find not one flaw.
Once thing I'll add is Huge size Doesn't = Huge sound. I used to get excited about huge drivers and think they were untouchable. In subs I'm still all about that. Loudspeakers where I cross to subs not so much. stick a 2150 or 4722 next to a 708 or htm 12 and your eyes will say the little guys don't stand a chance. That's not the way it works. Mfusick snuck a 305 (cheap but very well designed JBL with a 5" driver with an M2 style waveguide) in a GTG against JTR and many other heavy hitters and guys were blindly picky them as favorites.. not in an SPL contest of course but they sounded huge and detailed. Take the 2150.. everything above 500hz is handled by an area that's not that large... not that small either but without those dual 15s would lose some of that eye candy WOW factor. As for mid bass dynamics.. handle SBIR and floor/ ceiling bounce and any well designed sensitive speaker will keep up above 80hz to at reference levels. Bottom line, Physically bigger does not mean sounds bigger. Well designed with great on and off axis (off axis is the key to huge sound), good sensitivity so you have the dynamics mixed with good size woofers to keep up with the subs is the key in my book.. and proper room treatments to control the reflections (not all absorption
Someone asked why the Cinema speakers are crossed so low. It's because the 12s and 15s can only play so high until the begin to beam. That happens when the wavelength is the size of the driver. This is why you don't see large woofers crossed very high. It's not a cinema thing but a speaker thing.