Kyosho is out of the question, because though I make decent money I am not rich.
Choices are: (top to bottom has no reluvance just how i typed them)
AE
Mugen Seiki
Losi
CEN
Jammin'
Here's my take on this: First, let me say I'm not a very good driver, I hit a lot of stuff.
I've owned a OFNA 9.5 (crap) Mugen MBX5 ProSpec (tough as nails, handles like a dump truck- great beginner car, but hard to make it turn) Losi 8ight (fast, nimble, inexpensive, but "edgy" to drive) and a Jammin X1CR in buggies. I currently race only Truggy, and have an X1CRT. We have a LOT of local Xray drivers, and several AE drivers, although I've never driven either of the buggies. I've driven the Xray XT8 truggy and the old Xray XB8.
My "teammates" have driven the Xray 808 and the AE buggy, so I'll post what I can. So... here goes, in the order you posted:
AE: The buggy has THE most explosive acceleration of any of the cars you listed. It is VERY nimble, and seems to be stable in the rough, even without "Super Big Bore" shocks. The Jammin shocks will fit, and AE just came out with their own upgrades. They originally had some issues with leaky fuel tanks, but that appears to be fixed. There were also a few other issues, but the cars come with an "upgrade package" IN the box now. The truggy looks equally good, the local guys driving them are cleaning house with them. It is simple to set up- frankly there are not a lot of adjustment options. (buggy AND truggy.)
Mugen: I know ONE person with the new MBX6. I've looked it over, and quality looks top-notch, as expected for Mugen. The older cars were VERY stable and forgiving, but it was difficult to get rid of the tendacy to push. No new truggy yet, and the truggy has the same issue- a very pronounced push. Probably THE toughest of the tough when it comes to surviving crashes, with the possible exception being Xray. I firmly believe that the old MBX5 and MBX5T are THE BEST BEGINNER VEHICLES MADE. However, given that you come from a background of quick, agile onroad cars, this is probably not the choice for you. The new MBX6 might be however. It is a radical departure from the old MBX5 series. Slender, lightweight, nimble like the Losi and Xray.
Losi: Probably THE most nimble and aggressive on handling. VERY edgy, it will bite you if you push it hard. Parts wear is a bit excessive in my opinion, in particular the bushings for the front ackerman plate, and in the arms. The truggy has a VERY pronounced tendacy to eat rear ring and pinion gears, and the buggy less so but still unfavorable. Diff cases wear grooves in the crosspin area rapidly and have to be upgraded to the "heavy duty" cases with metal inserts to reduce that... in particular the center diff wears fast. It has a tendacy to spin the CVD crosspins on the front and rear out, even with locktite and obscene amounts of torque applied to the setscrews. To put it bluntly, it is a GREAT racecar for a driver with quick reflexes and who is smooth on the controls, and who likes to work on his equipment all the time- it is what I would call a "maintanance whore." On the plus side, parts are VERY inexpensive.
CEN: Sorry, I have no personal experience with this one at all, I don't personally know anyone who drives or has driven one.
Jammin: My personall favorite, but that is just exactly that, because it suits both my budget AND driving style and ability. I've owned both the X1CR and currently the X1CRT. The Jammin is VERY stable and forgiving, almost as much so as the Mugen, without the tendacy to push. It can ALMOST turn with the Losi, Xray, and Associated, it's very close, but it is a bit heavier and more sluggish on acceleration- I'd say it is a little less "athletic" than those 3. Parts wear is medium- not bad, but the plastics are a little soft so you have to be careful not to strip the screw holes in the "bulkheads," differential cases, and radio tray, and the arms develop slop faster than anything but the Losi. Fortunately parts are, like the Losi, inexpensive and readily available. I haven't driven the X2 CRT yet, but it appears to to be better all around with a lower center of gravity, weight moved more to the centerline for better stability, and better acceleration. The X2 buggy is about to be released, and there WILL be an upgrade kit from the X1 to the X2.
Xray: At first glance the 808 looks like a Losi clone, but it has MUCH better durability and a little more stability and traction, without giving up the ability to turn or the "athletic" acceleration. Nobody matches Xray on parts quality, period, not even Kyosho which is considerably more expensive. The only issue I have heard of with the Xray is rapid wear on the pinion bearings- but who cares about a $1 part? I've driven the XT8 truggy, (no 808 truggy yet!) and it is as nimble and aggressive as most buggies, but with more traction... that truggy absolutely rocks!
So, to summarize, here is a little chart: 1 best, higher is not as good, ranking the listed options + the Xray in order... note that in some cases #1 to #3 or #4 may be a very close thing- this is just ranking them in order based on my personal observatons: (Note that I'm only ranking the buggies, but the truggies from the same manufacturer pretty much follow suit.) No CEN ranking, I don't have any experience there.
Buggy Acceleration Turning Stability Durabilty Maint$
AE 1 3 3 4 4
Mugen 5 4 1 2 1
Losi 2(tie) 1(tie) 5 5 5
CEN * * * * *
Jammin 4 5 2 3 2
Xray 2 (tie) 1(tie) 4 1 3
Again, those are just my personal observations and experience. I'm sure some folks will disagree with some of it at the very least. I hope it is at least somewhat helpful to you.