Lisandro_P,
this depends very much on the driver.
Lowthers sound spectacular in backloaded horns (and rumours have it) also in bi-loaded horns like the famous TP-1 enclosure. TME, they wear out sonically with time, the long-term listening fatigue grows in your mind.
Any good paper cone driver will sound stunningly good when run in an open baffle, just take an old door, saw a hole in it, mount the driver, try it out.
I can recommend the Fertin FLB20EX very much, see my post in the high sensitivity driver thread. I listened to it, i bought it immeditately.
Before that and at the moment, i made a long-term listening experiment to see if i could live with such a driver and surprise,surprise, found that i could not live with the mud created by an enclosure anymore. As an intermediate solution, an old Focal 7N303 with a "neoflex" cone and a small tweeter for over 10kHz does a fine job.
But i disgress, you asked for fullrange drivers. There was an article in the German Klang+Ton magazine (3/2000) describing some drivers and showing fancy impedance curves. I could not believe these curves to be true (was the author out there to prove that drivers with whizzer cones are junk anyway?). Consider, if there is a phase shift of >360° (some Lowthers showed 3 times of that) and different parts of the diaphragm are radiating differnt frequencies but are mechanically linked together so a considerable degree, do the whizzer cones wait three periods silent until they radiate, or (more probable

) do they get ripped off the main cone then due to the phase shift? They should, according to the curves, but from own experineces with my Lowther, i can tell you they do not.
From own listening experinece i can tell that the Jordan drivers are just fabulous and i would consider some of them as fullrange drivers. The also survived the Klang + Ton article with flawless measuring reputation (no other driver did).
The Diatone driver is wonderful from 80 Hz to 16 kHz , just not so efficient. It is sold for quite some money by EIFL, Japan, it looks like cheap junk an probably is but it is a musical instrument. To get at beginner's level into widerange speakers, this driver would be my recommendation.
The Lowthers (and speakers derived from the lowther like the REPS1 and the German AER drivers) are well-suited for horn use and their frequency response makes them ideally suited for horn use but not for normal use(the horn boosts the low mids and the speaker needs thsi to sound balanced), they sound *speed-of-light* fast and very natural and open and the colour/detail resolution of the upper low end is hard to beat; the lower low end simply does not exist. But i know few folks sticking to Lowthers for longer than a few years, most (including me) sell their Lowthers after a while due to listeing fatigue.
The AER drivers seem to be an exception to some degree, they have no phase plug, the doubleVC is wound outside of the VC former and their diaphragm is softer than the Lowther one. Roumours have it the AER driver has not the typical Lowther "shout" but as tradeoff they lack dynamics and punch over the whole FR. THey certainly have the least longterm listning fatigue of all Lowther-like drivers.
The Jalabert/PHY driver is wide used for fullrange and open baffle applications, i did not hear it myself but my buddy Hartmut, whose preferences are very close to mine, complained about no treble and mids too coloured and PRaT not ok. The open baffle expert i recently consulted uses a PHY and seconds that but says that with himself aging, he more and more cannot stand treble and he loves the PHY's colorations. R.L.Andreoli developed an openbaffle speaker with a PHY and a tweeter of his choice added. I guess this driver is a question of taste like no other driver.
A french friend told me that Supravox is a very good choice if you happen to get a pair of properly manufactured drivers, their 215/2000 has no whizzer cone and can be ordered with an AlNiCo magnet or a field coil motor. Supravox also has an 8"er with whizzer cone and a wider variety of other drivers. Some of them have fancy performance concerning, efficiency, moving mass, freq.response, f_r.
However, as a dyed-in-the-wool engineer and being very quality oriented, i do not second sloppy manufacturing practices (magnets coming off, scratching VCs and the like) and feel urged to warn from Supravox. If you decide to risk this and give them a try, tell them straight you have heard about manufacturing problems from different sides (i bet the folks on the fullrange driver forum and the high efficiency speaker asylum having dealt with Supravox will second my warning) and that you want to know if this is true and what they undertook to get over that and that you will put particular focus on manufacturing quality and that you wold love to report on forums that the rumours are not true and just hot air , something like that , yo 'll find the right words
Well, then there is my own choice, the Fertin FLB20EX which sounds neutral on the warm side, very uncoloured but colourful, incredible detail resolution, wide 3D soundstaging (who needs surround

) with almost palpable body and heaps of air between sound sources, fantastic treble (in fact the "treble" arises not an issue at all, it is just natural and merges) . Transients are shocking, µdynamics are the best i heard so far. µdynamics, have to dwell on that, the speaker has sweetness and seductiveness unequalled to my experinece so far.
Another funny observation: the speaker sounds like a life act and if i walk ito the other room, it remains to sound like a life act (located in the other room). I had this with no other speaker, walking in anonter room and you have ,clearly audible, unmistakable, canned music playing.
As i wrote in my other post, all my wet dreams have come true. I will report here as soon as my speaker is running.