Hi,
I've stayed at both, Rambutan last December, The Quay a couple of years ago.
The Quay is in a good position as it's close to the centre of things on the riverside, plenty of bars and restaurants close by and Blue Chilli is a 10 min walk.
The better rooms overlooking the river are good and it's a stylish place.
Rambuttan Resort is a tuk tuk ride away from the action in BKK1, there's not a lot going on around the area but there is a local market close by and the Russian market is not far - still a tuk tuk ride away though. Rooms and service are great as it the pool and bar/restaurant area, although both can get busy with expats especially at weekends. Their chef, Mr Meanchy is really good. They have in house massage and their penthouse is a great room with a large Jacuzzi on it's own room terrace.
Cheers