Rakeback is hardly a consideration in MTTs since the ROI in them is alot higher than the rake which is a flat 10% (or less), so you dont lose alot of money from rake playing MTTs.
The lowest rake and the fishiest players are in GGNetwork (Natural8). 5% rake in MTTs and an option to buy/sell action. The $T builders doesnt even have rake... You also get 30% EV rakeback in a form of a roulette with prizes. Also, you start with 200BBs and theres ante from the beginning.
If you talk about SnGs, then you should definitely change from stars, but I dont know what site is best for them
For cash-games the best sites are on the Microgaming network (Unibet, Betsafe, Betsson) - the rake has the lowest cap of all the networks. The most you can rake in a hand is 3bb. And you get 30% rakeback for life if you sign up through the right refferal (otherwise you will have to level up). If you are a fan of HU cash this is the best place. The rake is capped at 1bb and there are microstakes HU tables.
The annoying thing is that they removed the sitout on next bb option, so you will have to wait for the right time to sitout before the bb hits you and if you use a HUD you will gather only the hands and stats that you put chips in the pot.
There are also MTTs there that start deep-stacked and have long blind levels, IDK what the playerpool is like skill-wise though...
For HUSnG, Tigergaming has the lowest rake of 5% for micros.
I hope I helped!