Best RO/DI filter for nanos?

i run a 30 gallon system. Hauling buckets to lfs is getting annoying, what the best RO/DI system that has a lower gpd. Does gpd affect filter life? I also have limited space, is its possible to get one that i can hookup real quick to faucet and then put away when im not using?

Price really isnt an option i just want something with easy replacement parts that will be around for awhile and do everything i need. I live in long island, new york if that affects what cartridges i should be shooting for