We’re talking too many years ago when I was a kid and for a short while lived in Onterrible. The only thing I remember very well is the smog and in the summer smog alerts – meaning if you have any kind of asthma, you should avoid being outside. I remember the winters being able to see Mt. Baldy and in the summer just seeing gray air w/no sign that mountains were even there.
From what I remember, Claremont was a nice area. Of course, that was so long ago. Things can change. Pomona back probably before I was born was supposed to be very nice. When I was a kid, it was to be avoided completely, dangerous, very bad.
Upland is supposed to be nice, also Alta Loma. I think generally the closer you are to the mountains, the better.
The traffic on the 10 or the 60 is brutal and makes the 15 look like a picnic.
Can’t stress enough, probably many others will agree. Rent there first. Best way to find out about the area.