Vietnam has the most features, but no ability to engineer them to match Chinese capabilities. The islands themselves are marginal, good for small landing strip and some basic installations, most need an inordinate amount of work and investment to become useful. Vietnam is simply incapable of producing a dredging company as large as Chinese CCCC, a byproduct of serving a country with 1.4B people. I think Mischief Reef alone reclaimed 1400 acres, about 10x than all Vietnamese dredging efforts. It's a massive undertaking but relative to goals. Vietnam's goal is just to claim stakes, which they can do with something as rudimentary as brick buildings, a dirt landing strip for supplies and DK1 rigs. Also see Philippines' Sierra Madre on Thomas Shoal, literally a beached ship to base a handful marines out of. China's goal is to push back USN, which requires a legit base, full runway for modern fighters, reinforced hangars and all associated support infrastructure. There's also work on geoengineering fresh water and agriculture to strengthen claims - turn feature into proper island for EEZ rights. If properly weaponized, it could make every USN asset in SCS vulnerable. During a shooting war, it would get wiped, but there's enough hardened infrastructure that US would expend substantial munitions. It's just another scale of construction and capabilities.