I use the Cibola, but have never used the 350, so I can't give you an honest comparison. From what I've seen, they have some similarities. I would go more for the Cibola because there's no screen to lie to you

and it comes with a lifetime warranty which the Garrett does not.
But for primarily park hunting I am going to suggest neither of those.
I will instead suggest the Tesoro Compadre. Yes, the $150 detector.
It runs at a high frequency (12 kHz) which will make it more sensitive to gold, and is better than the frequency on the 350 and almost as good as the Cibola.
The smaller 5" coil will be a blessing in a trashy areas, and almost every park is trashy.
It will give you about 6" of depth on most targets, which is where 90% of your finds will be anyway, no matter what detector you use.
It is also very lightweight and you can use it all day without getting tired. And again, there's the Tesoro lifetime warranty.
Good luck with your final choice.