(currently plat2 but been diamond many times, decaying) Played a lot of reksai this preseason, after never having played her before. Soo much fun and had lots of success, level 5 mastery already. Never tried going cinderhulk though, will have to try it after everyone keep saying it ;) I've mostly been going Stormraider's Surge (speed mastery) and Warrior -> Cleaver -> tanky with plenty of success. Usually snowball really hard and can 1v1 everyone in the midgame, awesome ganks early and can chase down anyone. Lately I've been testing Fervor though, and it's really strong if you know you're not going to be chasing mostly, but actually fighting head on, then it's probably stronger. But I find myself mostly wanting to gank/kill softies and get out where speed is better for sure. So it depends on what you're facing really.

Then depending on what you picked, I'd say your other items vary so much it's hard to say anything general. Like without speed mastery I probably go blue smite, but with it I can freely go Tracker's for that insane vision (really helps tbh), sometimes go Skirmisher's too (like vs strong Kha player) and then into whatever the game needs. I do like to carry early/midgame tho so I always go at least some damage, which means Warrior (tried devourer too actually and crushed those games, but feels cheesy?) into some damage, if snowballing I can even go Youmuu's (usually with Fervor, nice with IAS and movespeed) and/or Cleaver (CDR is so nice too) then Dead man's and other tanky stuff (usually Spirit Visage but it can vary depending on team). These are just some examples, other games maybe you want tanky earlier, or even locket, etc.

Definitely not saying what I'm doing is best, gonna try out the tanky route for a bit, see how it goes. Just had some success around plat3-2 soon 1 with my strategy.