It's very good. It solved the fundamentally stupid design decision of that series (walkers choosing random directions) by allowing you to section off walking routes.
Eh I wouldn't call it solving the problem more as making the workaround more obvious. You could place roadblocks and section off areas since at least pharaoh (having trouble remembering if this was the case in caesar), but the china game made it more obvious because you were encouraged to build districts surrounded by walls which helped each block more visually obvious. In the end though you still need a bit of external knowledge and whenever i go back to these games the first thing i do is i always check in a faq what the minimum walking distance is for a worker, then you arrive at the maximum length you can make a full district that is covered by a walker of each type. If you play without knowing this magic number, then you're still going to encounter the same problem in Emperor, you'll build your districts too long and your walkers won't be able to make a complete loop, or worst, will turn back mid way through, so you will experience intermittent shortages exactly like in the previous games.
This process is exactly the same in pharaoh, zeus or Emperor regardless if you then build walls after to make it more visually obvious, so if you had a problem with walker system in previous games, Emperor doesn't do anything to "fix" that.
Personally of the sierra city builders, i like all of them except the caesar games (all i remember now is being frustrated at things in caesar that would be fixed in later games, this is why im almost sure they didnt have roadblocks in it, that sounds like something that would have pissed me off), they each had something a little different. So if in zeus i found the main city/colony structure of missions annoying more then anything else, i liked how gods were handled and having your military derive from your wealthy classes able to afford arms and armor felt nicely thematic.
Anyways yeh get Emperor, it's a good game (chinese theme wasn't as much to my tastes either tbh and i preferred how much more organic looking my cities in pharaoh or zeus looked, but i guess you could argue that's part of the theme).
As for best builder games... I was halfway done writing 3 big paragraphs about my favorite city builder games before remembering op asked best "builder" games in general. Question is so big in scope i'll save everyone a tldr, if we include non city builders too then I might as well write a 20k word dissertation complete with graphs and statistics.
Sticking to just city builders, i'll just mention titles that i feel don't get talked about enough, namely Lelith: path of progress (steampunk themed modern sierra city builder style game which is legit pretty good) and Children of the Nile: Alexandria which is a sequel to pharaoh, only ditching the usual sierra city builder conventions and trying to be more like a simulation game. I'd say they succeeded pretty effectively and whilst many city builders have tried to replicate sierra city builders or refine sim citys formua, i legit can't think of many games that tried to simulate their population like Children of the nile did. The only one that comes to mind funnily enough is the Tropico series but there's probably a few more i'll kick myself for not remembering in a week or so's time.
Otherwise there's a bunch of city builders released on steam in the past few months but alas i'm too caught up in my backlog of games to try anything new atm. But chances are at least one of them is pretty good.