Hi Phil,
If we are talking about withdrawable bonus here, then I would say my maximum would be around the 15x (D+B) for a 100% bonus.
Because there are many different offers, I think the best way to measure
WR (as suggested by someone else here on the forum) is to always put it in terms of how many times the
bonus only has to be wagered.
e.g.
15x(D+B) @ 100% = 30x the bonus
15x(D+B) @ 50% = 45x the bonus
15x(D+B) @ 200% = 22.5x the bonus
Some casino's only state BxN, e.g. Intercasino is 25x the bonus (only)
So as I said, up to x30 is as high as I would go - anything beyond that is frankly, a total joke.