First of all you have to differentiate between synchromesh and non synchro, usually constant mesh, gearboxes, i haven’t found a synchro box all that pleasurable to use with the exception of the 16 speed unit as fitted by Daf in recent years, which is one of the best manual gearboxes of recent times IMHO.
I haven’t driven a Volvo or Scania manual box that i would call good, all baulked to varying degrees.
My first lorry was a S39 Foden so sported Fodens own 12 speed ‘crash’ box, basically a 4 speed box with 3 splits, however where it differed from the others was the 3 splits were unequal, so you didn’t do as Eaton Twin Splitter split each of the 4speeds into 3 splits, you had to learn the sequence.
It was a hard box to learn initially and it didn’t forgive mistakes, early models had the range split lever on the top RH of the slab of cast steel amusingly known as the dash (earlier model still the range shifer was a second gear lever 
), later, S40/S80 and onwards the range splitter moved down to the usual position on the gearlever, much nicer to use.
Once used to it the box was good to use, but hard work at first, i remember it affectionately because as i was told when i started, and he was right, once you mastered that everything else (bar some of the complicated multi sticked US boxes) would be a doddle afterwards, there is something to be said for a baptism of fire.
Daf fitted ZF’s splitter into their 2600 and 2800DKTD models, it was back to front in 2600 (can’t remember if the 2800 was back to front now, possibly), with 1st beside you and 6th/12th furthest away, but once used to it the box was fast and easy to use, with rapid gearshifts being possible.
One of the most unusual fitments was the 13 speed Fuller in an MAN 16,232, with column gearchange, again once you got used to it the thing was decent to use, later models the gearchange dropped to the floor as normal.
The same 13 speed Fuller was used in lots of models, good box.
Eaton Twin Splitter, 3 speed box, 3 equal splits, hated by many and i like most others played all sorts of tunes on the thing for the first month, but once you got used to it, and so long as you had a good garage who knew to keep the clutch/gear brake working properly there has not been a faster box put in any lorry i’ve driven, you could make almost uninterrupted constant progress with one of these because as fast as you could shift the gears the box would take it.
I covered several years with these in MAN F90’s, which i think was one of the best combinations, MAN engines revved up quickly and the revs dropped quickly so the box could take advantage of this.
99% of the time you used ETS without touching the clutch except for starting and stopping, just blipped or lifted off the throttle to allow the next gear shift, whether combined with a pre selected range split or not, to engage.
Where the clutch/gear brake helped was on really steep hills where in the low gears you wanted fast gearchanges, fast as you could ram the clutch pedal to the floor and release it the next gear was engaged.
Pulling away from junctions if you had a decent engine the vehicle would romp away in a fashion those who have only driven modern lorries can only imagine.
Fuller Roadranger, like Lucy i liked these, a generally decent box, i had these in two memorable artics, one being a Leyland Buffallo, which whilst not the most powerful engine the engine was perfectly matched to the gearing and with rapid changes you make make some good progress on the road, a thoroughly pleasant and satisfying drive IMHO.
Matched to a decent ■■■■■■■ the 8 normal speeds were more than enough, in practice you’d only use it in the top 6 gears, easy and simple to use.
ZF’s slapover box, seemingly hated by many but i found it a good box to use, particularly in square Axors, a lorry also hated by many and indeed the auto version was sod all to write home about, but with a decent manual box one of the most honest basic working lorries of the last 15 years IMHO.
Now as for the most hated boxes, that for me has to be the Merc Powerliner thing as mentioned above, to me it didn’t have one redeeming feature, though i dare say for some who might struggle to shift some of the horrid synchromesh boxes they would have been easier, i hated the things and if i had a £ for every time it dumped me in neutral at the most inopportune moments i could retire early.
I also never really liked the David Brown 6 speed, though generally matched to a hateful Gardner LXB/LXC so sloooooow and frustrating was the order of the day so i’m probably being unfair to the box.
Spicer’s splitter didn’t have many fans, but i never found them particularly irksome.
Most gearboxes have redeeming features, i don’t like driving arsetronic for example (cheers Norb 
) but there is no denying its reliability is second to none, and you learn to make the most of whatever good points a box has and make the most of them.
I dislike what Daf has been doing recently in defaulting to eco with arsetronic, driven in manual mode they can be as good most modern automated manuals, defaulting to eco is a mistake.
My favourite box was Eaton Twin Splitter, with Roadranger coming a close second, Foden’s 12 speed a third for it’s uniqueness and awkwardness (typical Cheshire i’ll do it my bloody way Frank, me dad hailed from Cheshire so know all about stubborn 
) as much as anything else.
. Pretty unique at the time.
