This question got me thinking so much, I'm yet to vote.
I've driven across many states of our wonderfully diverse country, here's how I understand them.
1. TN : home state, driven on all kinds of roads, extensively. Fully agree that they're the best.
2. KL : multiple short trips to Munnar (roads and traffic are ok, but also since one touches very little of KL). Drove across some parts, mixed experiences. Drove once from North KL to Trivandrum once in a TUV AMT. Suffice to say, I don't want to repeat that experience. Narrow roads, rash bus drivers, takes too long to cover distances, quite strenuous.
3. AP : Regular visits to Hyd and Vizag, from Chennai. Highways are acceptably good, State roads are also ok, traffic density manageable. Traffic in Hyd is a very different game, though. Overall, not the best, but far from the worst.
4. KA : Regular visits to Bangalore, but have driven from Goa to Mangalore to Udupi, apart from certain trips to Dharmasthala, etc. More patchwork than AP, but in other aspects, remarkably similar. Bangalore traffic is the worst I've driven in.
5. Goa : Drove through thrice, over a space of 15 years. Certainly a breeze to drive across, even if the backroads seem narrow. Not the best, certainly nowhere near the worst. I'm ignoring the weekend traffic that goes crazy, because I've driven on weekdays and it seems to be a different place compared to weekends.
6. MH : Local drives in Bombay (long back), drove from GJ to Nasik to Pune to Goa in 2016. Also, drove a free times through the Nirmal-Nagpur-Pench stretch. Patchwork on top of patchwork!! Roads that can otherwise be great are ruined just by the poor surface, much more so on the coastal side than the central highways. But most people seemed to drive sensibly, roads are generally wide. Overall, falls somewhere in the middle.
7. GJ : Entered from RJ, exited near Surat, going towards Saputara. Drove only once, only on the NH. The Ahmedabad-Baroda expressway was fantastic, if very boring. Rest of it was also uneventful, encountered the most disciplined driving in my 15~16 years of driving/riding. But as soon as I hit the narrow back roads, that good impression dissipated, they seemed almost uncared for. Overall, very far from being called bad.
8. RJ : Lived in Jaipur for 6 months, drove across the state multiple times. Excellent highways, wide and straight. Seriously fast. But other roads are not as good, with poor surface (wavy, rough) and uncharacteristically narrow in places, especially rural ones. Overall, just as good as GJ.
9. TS : Not very different from AP, by and large.
10. MP : Only drove the Nagpur-Pench-UP stretch a few times, all in the last 11 months. The NH is great, but too little experience to rate the whole state. Doesn't seem too bad on the whole, especially when compared to its northern neighbour, UP.
11. HR : Lived for 3 years in this region, 2013 to 2016. Horrible roads, uncouth folks, uncivilised and dangerous driving, zero value for life, frequent roadworks but with no palpable result. Traffic jams on NH8 & NH1, for no ostensible reason! Certainly a good contender for the worst roads award. One trick I used liberally was to go close to a HR51/HR55 registered taxi and honk. They never let you overtake, they'll accelerate. I make that fellow my pilot and let him do the hardwork of braking and accelerating, I just follow through, while honking at him once in a while. (Bad? Maybe. But when in Rome...)
12. PB : Drove Delhi-Amritsar-Pathankot twice, through Hisar to Ludhiana section twice, apart from cutting through the state on other tours. Far better than HR, but not comparable to RJ. (Maybe the lip-smackingly good food makes it better. I know it shouldn't really be a parameter while judging a road... But while on a drive, the food makes a huge difference!) Overall, somewhere above the middle.
13. HP : Visited multiple places there, went to Leh via Kashmir and returned via Manali. Topography poses various limits, but the roads are quite poor if viewed in isolation (the scenery is not a parameter, but if it was, I'd rate Himachali roads as the best. The combo of views, curves, food, climate makes it unparalleled). Within the parameters of this evaluation, somewhere near the bottom, but with its valid reasons, it deserves to be excused.
14. JK : Drove there only once, in 2014, went Pathankot-JK-Leh-Manali. Drive of a lifetime, but within the parameters of this poll, with my limited experience, they were nothing short of extraordinary. Despite all the constraints, the BRO has achieved magic (& does so repeatedly!). Far from the worst, but in pure road terms, can't be the best.
15. UK : Visited multiple places there, major tourist spots and off beat locations over several trips. Given the natural constraints, quite a commendable job!! Far from the worst, very far indeed.
16. BR : Very limited experience, circa 2017, but had low expectations to begin with. Suffice to say, Bihar driving experience meet my low expectations. Only saving grace seemed to be slightly lower traffic density.
17. No driving experience in the places I've not mentioned, so can't judge. I'd excuse the North Eastern States considering the limited political & financial love they've received, plus the immense natural challenges posed by topography and weather.
I'm not done yet.
18. UP (Uttar Pradesh, formally. Ulta-Pradesh, in my books) : Drove from Faridabad/Gurgaon/Dharuhera/Delhi to Agra via all possible routes, so many times that I've lost count. Experience started in 2013, with very high frequency (2~3 times a month), but continues till date, with low frequency of once in 6 months or so. Drove the MP-Agra-Delhi route thrice, in last 11 months, even as recently as Aug-2021. Drove across the state while visiting Nepal, in 2014. Unforgettably bad experience, especially on the concrete sections were road direction and the "lay" of the concrete are not the same!
The only place that can make Haryana driving experience seem better, is UP. Road surface is as good/bad as HR, but the traffic is even crazier. Cows everywhere (God forbid you touch them, you'll just be butchered mercilessly), Splendors in the middle of the NH doing 40kmph (don't bother honking, he won't move), unpredictable and unscientific speedbreakers ON the highway, not on the roads joining the highway (this much more prevalent on state highways than NHs). Tractors getting on and off the highway as they please, driving in the opposite direction, in the overtaking lane (actually, wherever they please). And when you enter the cities, Brownian motion would seem more organised. Funnily, my HR registered Alto used to get more respect than UP registered white Fortuners! (Rowdy reputation of HR drivers certainly helped me sometimes). The cops "elevate" this driving experience even more, in unimaginable ways. (A Kanpur SI wouldn't believe that someone would stop at a petrol station to use the restroom. We were interrogated for 30mins until we showed our company ID cards and assured him that in our home state, we used restrooms).
Overall, I'd rate UP as the worst. But my disclaimer here is:
1. My KL experience is limited compared to UP & HR experience.
2. I have no experience of the NorthEast.
So, that's my ~1.5lakh km driving experience summarised
I voted, for Ulta-Pradesh.