FWIW, I'm currently in transition, myself. I use a combination of numerous (quite a few smaller) single external HDDs (not all at once), SATA SSDs, Cloud, and increasingly NAS. My external SSDs are usually for running VMs and for larger data files that may contain data requiring they be on their own (protected) drive. I also have several Corsair Voyager GTX 256gb flash drives, which use SSD controllers and essentially are SSDs in a flash drive configuration. My HDDs are for things I don't need fast access to, like videos, pictures, and older files, plus a drive for CCC to maintain a bootable clone of the main disk. Some of the HDDs have been duplicates if it is data not stored elsewhere. I use Dropbox but increasingly less in favor of (HDD-based) NAS, because I know what quality hard drives are being used, know that I have redundancy, and could access it via a wired connection if need be. I'm moving in the direction of reducing the number of externals, as some of my 2.5' HDDs are nearing the end of their service life, and most of the data they hold can be placed on the personal cloud with superior integrity. I've also recently started using DVD-Rs, which is ironic as I never used them when every computer I owned had a DVD drive built into it...
If you want wireless but something with more flexibility than DropBox or iCloud (size, speed, known security, and known redundancy), IMO NAS is worth investigating. For many people, it offers a single solution that can satisfy a variety of needs/preferences that historically may have required multiple mediums to accomplish.
