Hi,
I see that the best vinyl flooring company in SG should be Evorich already as I've used EvoHERF vinyl from them for my whole place since 10yrs ago & it is still doing very well now. Direct contractor is better but you must know how to request them to execute ur reno work generally otherwise interior designer is better as they're a one-stop firms who're able to execute everything from 3D drawing design ideas to reno works. Advantage for vinyl is that they're the most suitable choice for a new, fast & durable flooring if you wana overlay or makeover. Disadvantage is that they cannot tahan heavy & sharp objects.
My sister also used Evorich last year. Perhaps you can contact them for advise first.