Entertainment and 97%+ slots don't really go hand in hand. Realistically, the 'sweet spot' for slots always tended to hover around the 96 percent onwards mark, as many of the best games I remember would be in and around that. Often, 96.5 would be the benchmark.
Just that the variance was distributed more evenly and kept things ticking along, and the player engaged!
Of the 96+ variety, there are a few that I completely didn't Google but then remembered for their gameplay
Gonzo Quest Megaways (which in hindsight is actually a decent little game)
& many more, I'm sure. I ain't about to list them all, as it's ultimately subjective, feels like homework, and most games have probably been pulled anyway
To me, an 'entertaining' slot should keep the player wanting to carry on playing because they're involved in the proceedings, with well-timed wins punctuating the lean spells, and bonuses not too infrequent, but just enough 'around the corner' to keep you plugging away. A random feature or two thrown in also helps, a la Thunderstruck II's Shitstorms and so forth.
Used to be that developers could cram all these features into a game whilst keeping RTP pretty high. There'd always be the games like 'Bloodsuckers' that were used purely for wagering purposes, boasting around 98% RTP or so, but no one played them for entertainment, as Pick-Me coffin bonuses weren't exactly the height of ecstasy.
But good luck trying to find a high-RTP entertaining game these days, as I don't think they're being made!