Personally, I prefer high RTP games, not slots, though. In the long run, you can get close to 100% RTP on in-house games with bonuses and promotion prizes. That's my strategy - I don't like low odds on my side 
There’s no such thing as 100%. The closest RTP you can get is 99.5% if you play perfect Blackjack based on the strategy and this will only possible if you will consider th extend strategy on the matrix.
In reality, It’s very hard to play a gambling game with close to 100% RTP because all games is designed with house advantage.