Honestly they both need to be gone. Then our metagame would be complete. Sand is the lesser of the 4 evils. You have sun. You have people spaming flare blitz. You have rain you have people spamming boosted surfs and hydropumps. In sand you only have 2 threats thats really can be dangerous. In sun and rain you have 30+ and 40+ pokemon respectively coming at you with boosted attacks with no set up.
Edit: Yeah you switch in latios and then they switch in naitorai. Now what? They leech seed your next switch in and they bring in a rain abuser. You switch back in latios and they go back to naitorai. See where this is going? And even if you try to bring in a powerhouse most teams are carrying gliscor to stop them.
So you are complaining because basic pokemon dictates that nearly everything can be checked? If Latios forced out their threat, I'm good. The large majority of people so far have found effective ways to deal with it.
And lol 30-40 sun sweepers. Let's be real, there are like 6 viable users of Chlorophyll (Venusaur, Sawsbuck, Shifty, Exeggutor, Tangrowth, Victreebel), and of those Venusaur stands out far ahead as the best - the other five are second-class with the issues they encounter. As for fire-types, there are a few UUs/BLs that
can be used (Arcanine, Darmanitan, Infernape), but really how many of those have you faced? You'll see Heatran, Blaziken, and Volcarona. Maybe Solar Power Charizard. So overall, that's like 10 viable users of Drought competing for 3 or so slots on a team.
Idk where the "rain is everywhere on the ladder" thing is coming from, I see more sand than rain, and tbh i've found sun teams to be more threatening than rain teams. I mean, what the hell do you switch into Blaziken(or Hihidaruma) in the sun?
The only thing rain has forced me to do is run a grass or electric type or latios on my teams, but aside from that i've not found it all that threatening(though well built and played teams that do have a well though out plan to deal with nattorei/birijion and fast electrics are still tough to beat, but they are rare).
Yeah, rain is good but it isn't any more threatening than Sand. Sand has faster sweepers like RP Terakion/Landorus and SDExcadrill, but Rain has more power off the bat for lower speed.
As far as switching into Blaziken under sun, there really isn't anything that comes to mind other than Scarf Chandelure. It can still be dealt with through Flare Blitz recoil, cockblocking HJK with Protect, and keeping offensive pressure to prevent it from switching in freely. It also needs a turn to SD (unless it is MixKen, which is downright terrifying).
HP Ice MixKen can be stopped by Slowbro and Kingdra, who can Thunder Wave and Rain Dance (and then Dragon Dance on your Venusaur switch), respectively, to cause problems for the team overall. Any scarfer with more than base 80 speed will fare decently as well - ScarfChomp isn't OHKOd by anything but HP Ice and threatens with EQ. Terakion can't take HJK and Landorus can't do HP Ice or Fire Blast/Blitz, but still outspeeds. ScarfLatios and Rotom-W outrun it at +1 as well. Then there is priority (MH Whimsicott and Voltolos count here too), hazards, LO recoil, and status...
SN: Rain doesn't particularly check Blaziken either. All you need is one turn to SD and you can OHKO things that rain usually runs (LOStarmie, SpecsTornadus, Politoed) with HJK + Stone Edge alone.
EDIT: The current Drizzle + SwSw ban is just as complex as the 1 sweeper ban currently being discussed. With a larger number of threats and factors surfacing with each new generation and game, it is natural to expect that more precise methods are required to achieve the most desirable metagame.