I've owned both. I prefer Palace Guard by a mile.

Hit either row of 4 snap targets for an extra ball. Hit A-E on top for an extra ball (no need to hit "C" last). The bottom outlanes and center drain are also A-E switches to help build extra balls.

Scoring is more balanced, as there are no 500 point shots. Hitting snap targets either light 10 point pop bumpers or 100 point upper targets. It makes the pop bumper area much more valuable.

It's a classic GTL add-a-ball where you can be on your last ball, terrible score, and have a great ball and build back up a few balls and end up with a great score. You are never out of the game. On Royal Guard, hit the wrong letter on top or miss a 500 point exit and you're pretty much screwed.

Although I live in the add-a-ball land of Wisconsin, I spent a good part of my youth around replay games. Royal Guard was one tough game to beat (and I considered myself a pretty good player). I almost never won a game on score (4500 was the first replay) - always on the snaps or A-E feature. We moved back to Wisconsin - and I hated add-a-balls. It wasn't until I played Palace Guard that I really appreciated the difference. I could score points!

Now, I gravitate toward add-a-balls. To me, it makes more sense to extend a game at home than to win games that are already free.