Well here's mister know it all Played both a lot. I like the flintstones for the game, bowling alley, sounds are great. Downsides are art i.m.o.
R&B although I do not know the cartoon, I like the theme, call outs, music, art, tri-ball and interactive toys on the playfield and the backglass.
Both are great games, R&B should be a little bit cheaper than Flintstones.
Both will be fine as first machine.
If you can only buy one........Flintstones would be my choice, just because it is a Williams game.