In terms of everything apart from promotions, bet365 is defo the best. Most markets, best cash out, has nicest layout by far. However they are shit for free bets.
I think promotions are not bad at bet365. In fact if someone is signing up at bookmaker only for single promo of 20 euro it's not worth it. In the long term having coverage of all sports and tons of choices is better than some 20, even 50 euro bonus. Bet365 is definitely one of the best, if not the best.