Most lobbies seem to be 500 - 550pp, some 450. I love 450-550pp but do wish more were 400 or below, slower cars are so much more relaxed and there's not as much bashing about, more clean overtaking it's more of a hard cruise than a race, focusing more on apex than braking.
Also with different PP not used as much you open up a new world of competitve cars. I like them all at the end of the day, except when you get to 600 and above where rules have to be stricter in order for the race to be fair. A lot of people moan about race cars in 500ish PP range but most race cars are even with road cars at that performance level anyway. Although not a full on race car, I've got a 550PP FXX and 550PP McLaren F1 and they handle well but slow on the straights, making them even with normal cars like BMW M5, Civic etc. Same with Touring cars and GT3 type cars.
Sport tyres of any grade (preferably hard) make races much better IMO it feels a lot better and real, racing softs which most rooms use don't feel right at all, in fact I wish PD would ban them completely on non racing cars it would be a game changer. Course there's nothing stopping you putting RS on a normal car in real life but you can't have that attitude or this would happen- 99% of people will use them for the sake of them having the most grip on the game. What would change this is if GT did what Forza do (never gona happen) and make better tyres drastically increase PP, that way there would be no way in hell a Focus or Civic would be owning supercars arounf the ring. That way there would be a hell of a lot more range, if you wanted to put lowest grade tyres on a car so you could get max HP, at the risk of possibly being more inconsistent and slower round turns, then you could, or the other way round with more grip less power.
At the monent it's only weight / power that affects cars, and that doesn't work so well if they all have the same tyres as so many cars that should be good get left out online, makes them completely worthless for anything other than crusing. Then there's the FF ownage, all because of racing soft and the super grip and super speed they give you, forget about wheelspin in FF on RS, just mash accel and get a perfect angle and exit through any corner with no challenge at all. Lessen the tyres and the field is much more even.