Accept that the bonus timing is random
Choosing your bet does not tell you when the bonus round will start. Nobody can know in advance how often it comes in Beware The Deep Megaways, and the result of one session is random whatever the RTP. An RTP of 96.51 per cent describes the return over a very large number of rounds, not your next session. Keep each session within the stake you can afford to lose.
Deciding whether the RTP version matters to you starts with the game rules, because only they show which version runs here. The three versions differ by very small margins, so that gap is minor next to the luck of a single session. Read the game rules before the first spin.
Deciding to chase the top prize is up to you, but the maximum win of Beware The Deep Megaways is a ceiling reached very rarely. Read it as the upper limit of the game, not as an expected result. The top figure is a multiple of your bet, so it rises in money as your stake rises.