The bad news - I doubt there will ever be the total number of mods for SE that there are for the original. Some excellent modders moved on years ago.
The good news - Some of the *very important* mods are already in beta for SE. Also, who knows, maybe a new generation of excellent SE modders are poised to surpass what was done for the original.
I own both on the PC and haven't even tried SE yet. I run a lightly modded original. 11 mods, not counting the DLC's or hi-res packs. Basically, all the unofficial essentials plus things like purity, skyrim immersive creatures, ELFX, etc.. I have the game tweaked just right for my aging system and, from the screenies/vids I've seen, my original still looks better, so no reason for me to go with SE.
Bethesda was smart to 'give' SE to those PC users who have the original plus all the DLC's. They recognize that a hefty percentage of their game's 'success' is due to the ability to mod the game. Putting the game into these modders hands (for free) ensures that many, many mods will be made for Skyrim Special Edition.
If I had to choose from a fresh start I would go with SE, with the hopes that all the mods that you'll ever need will be produced/converted. Plus, you can always mod it to the tilt yourself. I've done some light modding. The creation kit can be very 'convoluted' at times but if you have patience you can do 'almost' anything.