Now that Wano has ended and many people have voiced their pros and cons about the arc, I thought this would be an interesting thing to post here, because it gives an idea about where Oda concentrated his writing and drawing efforts while he developed this particular storyline.
THE TOP 50 CHARACTERS IN ALL OF WANO WITH THE MOST APPEARANCES
Monkey D. Luffy - 1689
Kaido - 989
Roronoa Zoro - 922
Kin'emon - 684
Kozuki Momonosuke - 674
Sanji - 573
O-Kiku - 484
Yamato - 479
Charlotte Linlin (Big Mom) - 471
Kozuki Oden - 458
Nami - 453
Kawamatsu - 431
Queen - 421
Trafalgar D. Water Law - 407
O-Tama - 400
Kozuki Hiyori - 357
Raizo - 353
Nico Robin - 345
Eustass Kid - 340
Kurozumi Orochi - 339
Usopp - 330
Denjiro - 320
Tony Tony Chopper - 319
Shinobu - 306
Franky - 305
Inuarashi - 302
Hyogoro - 285
Nekomamushi - 271
Ashura Doji - 270
King - 268
Kurozumi Kanjuro - 258
Napoleon - 253
Brook - 223
Komachiyo - 190
Jinbe - 188
Basil Hawkins - 187
Killer - 185
Marco - 169
Ulti - 149
Izo - 145
O-Toko - 144
X Drake - 142
Shimotsuki Yasuie - 141
Kozuki Sukiyaki - 131
Black Maria - 119
Thousand Sunny - 118
Sasaki - 118
Scratchmen Apoo - 117
Page One - 116
Zeus - 112
***RUNNER-UPS:***
Onimaru - 107
Who's Who - 105
Carrot - 104
Kozuki Toki - 103
Gol D. Roger - 96
Jack - 95
Prometheus - 82
Gama Pyonnosuke - 82
Aramaki (Ryokugyu) - 80
O-Tsuru - 79
Fukurokuju - 78
(Eye-Scar CP0 Member) - 76
Speed - 74
Edward Newgate (Whitebeard) - 74
Babanuki - 66
The methodology is all explained in the reddit thread. Credit to Chris_Mic: https://www.reddit.com/r/OnePiece/comments/wvkjan/a_comprehensive_breakdown_of_wanos_panels/
Personally, I was surprised about how well Kiku ranked, and that Aramaki managed to get that high despite being in just 3 or so chapters, to the point of surpassing Fukurokuju.
UPDATE:
I also found this quite old list from the now defunct Oro Jackson that includes panel time from chapters 1 to 908. If anyone wants to do the math with how it adds up with the above, be my guest.
Monkey D. Luffy - 15147
Nami - 7302
Sanji - 6636
Usopp - 6552
Roronoa Zoro - 6307
Tony Tony Chopper - 4638
Nico Robin - 3566
Franky - 2966
Brook - 1968
Nefertari Vivi - 1588
Trafalgar Law - 1476
Jinbe - 1084
Donquixote Doflamingo - 1031
Portgas D. Ace - 856
Crocodile - 830
Rob Lucci - 795
Buggy - 772
Charlotte Linlin - 660
Bentham - 656
Caesar Clown - 646
Kin'emon - 625
Kyros - 607
Enel - 600
Kaku - 589
Rebecca - 550
Carrot - 549
Smoker - 529
Arlong - 527
Charlotte Katakuri - 517
Hatchan/Iceburg - 508
Tashigi - 493
Kalifa - 483
Paulie - 468
Sabo - 425
Wiper - 422
Oars - 406
Galdino - 405
Hody Jones - 403
Shirahoshi - 400
Capone Bege - 394
Blueno - 385
Edward Newgate - 384
Charlotte Pudding - 376
Keimi - 373
Spandam - 369
Emporio Ivankov - 360
Pedro - 357
Don Krieg - 354
Gan Fall - 348
Boa Hancock/ Bartolomeo - 347
From here: https://www.reddit.com/r/OnePiece/comments/ae53et/top_50_characters_with_most_manga_panels_time/