Whatever works for you…
OK that’s an oversimplified conclusion despite it’s inherent logic and accuracy.
However, what works for you isn’t necessarily license compliant - but it should and in good working spec compliant order at the very least. After all, if operating outside of a license or license-free/exempt status isn’t bad enough, running with gear that’s unclean and unstable is a pretty awesome way to get your collar felt, as we’d say in the UK and almostly certainly be up in front of a judge eventually - and the odds on a fair cop arrest and subsequent sentencing being overturned borders on nil.
Anyway, returning to the main subject - the best item is one that suits your needs and that’s literally spec-wise the end of story.
So assuming you want flexible, even if you can only go on-air under a limitation of one mode and dual allocation, a type certified export type set is probably where you’d go, and use appropriately. Note, however, that if you got them professionally tested, most are pretty borderline compliant at best - especially the CB market focused sets. The equivs marketed to the ham world (which was really just a way of getting around import/export restrictions by selling to users who aren’t required to use TA/Certification compliant gear as technical operators, making it easy to import those ham market units and non-ham versions here in the UK as as a ham operator) are often subject to better QC from the outset, but that’s no guarantee and even then benefit from adjustment and realignment to get them basically not-foul emmision wise).
Ultimately, and I say this noting that most can’t legally use them and even where rules are more flexible - use of will still contravene most licensed CB usage rules - so it’s for observation I mention, the best rigs on the market, used and new, are non-export model 10m ham transceivers that are 26-30 MHz Tx unrestricted and usable VFO mode and channelised/preset mode.
These, where used legally for on-air ops and where you can legally support possession for Rx only use, are about as good as true single-band sets go. They are way ahead of the game, quality and factory setup spec wise and emissions compliancy is again as good as the QC which is way better than that of ‘export’ rigs. However, you will have to swallow a price premium.
So if we venture into rigs that you could potentially use, although absolutely not legit usable on 11m CB frequencies in the UK and Europe typically, are ham multi mode HF rigs. Whether you go for full 0.5-30mhz example or a more limited band focused item with 10m provision, these are literally as good as it gets outside of some professional Plessey and other major makes destined for military and serious restricted user possession and usage services. I’ve used some of those pro sets under appropriate temporary license or under guest usage and whilst they aren’t necessarily a big jump over top notch ham gear, they are definitely a disproportionate priced step up.
So that’s all well and good, and factoring in there are some auto-atu equipped or have sync connections for suitabley equipped auto-atu units, you’ve a lot of scope for listening across the board and 11m Tx use where permitted using permitted antenna setups and permitted output levels.
Of the old-school era units, pre millennium stuff, Yaseu FT-7xx era gear were (and still pretty awesome still) digital PLL synth type units from the 90s. Predating PLL synth stuff, probably the most accessible (given such items are hard to source, then and now) example would be a US market FT-101. Those had 11m coverage as a band selection and if your main CB focus is users operating on FCC mandated CB frequencies or other countries reuse of the spec, then these give you AM/SSB operation that literally walks over any CB gear for Rx performance and TX cleanliness if left factory spec. The FT-101 series can be retrofitted to PLL synthesis if you are hands dirty inclined and have decent test instruments to test and calibrate against.
But, whilst looking at a seriously sh*t disproportionate value in Tx unlocked state to use as a CB, ironically the FT-818 or FT-817 predecessor are actually great potential candidates. Aside from being modern rig compact, mobile/portable/transportable ready, they are also QRP power level sets which is easier to use discretely with stealth in mind. So as a potentially 27mhz operation Tx wise, all you’d need is a suitable synchronized auto atu and you could do a ■■■■ load of cross-HF listening even on a CB legal spec antenna or 11m dipole, and if you are curiously interested in data modes and CW, it’s out of the box a ■■■■■■ good candidate as an extreme way of getting the best low-power rig for CB where you can pull it off.
Normally I wouldn’t write such an article since it’s content could be construed as encouraging bad behaviour, but when you look at all the BS reasoning over what was/is the best CB rig, the answer simply is none of the marketed CB rigs, the real contenders are 10m and HF ham gear outside of pro equipment inclusion. I recently got an FT-818 as a HF/6M/2M/70cms QRP ready portable in hope I’ll eventually exploit it’s QRP usage outdoors legally, but it was how unsuprisingly clean it is on 10m, and both restrained and discrete once setup with an auto-atu I already had that used the same synch system and have tuned around the UK/US and EU 11m segments it inspired just how suitable it was as a potential (if pricey) one time purchase for those CB fans who maybe want to have a lot of serious radio scope in one box when they can legally exploit it on-air as well as as a gen-coverage receiver.
But I imagine the number of interested at the price tag wouldn’t exceed the fingers and thumb count of both hands.
That said, in fairness, there are some pretty well evolved potentially notable examples of single band/mode CB rigs out there, especially where you want discrete and compact and easily transportable/portable ready and a HT isn’t suitable or wanted. We see very few of those here, but given 11m CB is fairly much heading into niche interest ghost town territory or extreme wild west anarchy at it’s extremes here, I’m not overly surprised we see so few CEPT market variants of the more interesting Japanese/Chinese US and international market sets retailed outside of eBay etc.
Still, all said, there’s definitely best rig choice for you out there if you are clear about your needs and usage, inside and beyond CB specific market stuff.
But given there are, especially for town and county wide ‘local’ usage, much better and evolved VHF/UHF systems, maybe the while concept of a potential best 11m CB is redundant a subject.
As ever, you’ll do what you will and if you’re content with CB in whatever state of activity and usage you encounter in your locale - then keep it alive by not letting the frequencies get taken away due to dead air=ripe for reallocation reasoning you let happen.