Muwaileh works on value and it holds up. You get noticeably more space for your money than anywhere comparable across the border, and E311 access is direct. Al Mamsha changed the area, it's one of the few properly walkable spots in Sharjah, shops and cafés at ground level and no cars on the main spine. Sitting next to University City keeps it lively and means plenty of casual food options. Supermarkets, clinics and schools are all close.
The honest downside is the Dubai commute at peak, budget an hour each way, sometimes more. Parking around the older blocks gets tight in the evenings too. For families, or anyone working in Sharjah or northern Dubai, it's hard to beat on price.