I've been playing this ladder quite a lot, and I'm in love with it. I definitely don't think any of the buffs need changing, as these "ranks" are not absolute and giving anything +20 or more would throw the metagame too far out of whack, I reckon.
Regardless, here are some Pokémon I've loved playing with:
Guts Swellow, with 140 base speed and the old STAB 140 BP Facade coming off of 100 base attack is an extraordinary physical sweeper that can decimate entire teams once any Rock/Steel types are disposed of. Even when they're not, you can always U-turn out of them.
On the more defensive side of things, Lickilicky is bulk incarnate. 120/110/110 defences with Wish, Heal Bell and Dragon Tail make him a fantastic cleric and phazer. Nice 100/90 attacking stats, too, and access to SD.
My Sandstorm team is doing extremely well - Eviolite Hippopotas is a great mixed wall, better than Hippowdon from my experience; Golurk has nice bulk and hits like a tank (I use SubPunch personally, always seems to catch them off guard); and Seismitoad is extremely versatile, with a 120/100/90/100/90/89 spread and a fantastic typing and resistance in Water Absorb. The centrepiece of the team, however, is Regirock. 95/215/115 defences with that special defence increased by 1.5x because of Sandstorm. 115 attack. Put heavy investment into HP and SpDef and no-one can take him down easily. I've swept whole teams with Curse/RestTalk/Rock Slide once I've taken care of any phazers/taunters, even though many regard it a tactic that is a vestige of a bygone era.
As mentioned before, Manectric is indeed an extremely useful sweeper/scout.
After a Hone Claws, Hustle Durant is pretty deadly too.
Oh, and I've come up against WaterBomb's DD Whiscash... in the rain, that thing destroyed me. 6-0. I've fought them outside of rain and found them manageable, but one miscalculation in the wet conditions and I was gone.
Man, I'll be sad when Tier Shift is gone. :( I don't think I'd play anything else if it were a permanent OM.