This is a wonderful site, but uploading a lot here can be a headache. Is it easier to just create a tumblr account and upload things from there?

I'm looking for a site I can just link my creations to sfs and mediafire.

Easier for you to do; harder for your audience to find. Tumblr's search function is famously crap. Only you can do that cost/benefit analysis.

Doing one now does not preclude doing the other later as well, though. And the MTS process gets easier with experience, as your picture taking skills improve and you grasp why things are done the way they are here. If a tumblr is something you think you would enjoy, you may as well make one and see how you like it. Ditto any other platform.

A lot of people actually do both! Putting creations up here has the advantage of your uploads to reach more people, and I actually don't find it so difficult to upload things here.

If you are uploading a CC free lot, here is not that hard.
I think having both is best. Here is also another file hosting site should file share or whatever go down. You should also go into your profile here and add 'your site'. So if you click my profile and go to 'signature and more' you will see I have Home page:click here. That takes you right to my Tumblr (even though it looks like its not going to my downloads anymore) Still things like that, linking the sites you use also help people find you. But definitely get a Tumblr, but don't expect it to be easy to use, I find it a PITB.
The one really nice thing about getting lots from here is this site does not allow creators to just upload lots full of crap like hitching hacks and mail box recolours. Yes you have to make sure the lots are clean. maybe annoying as an uploader but very nice as a downloader and I do both.

Yeah, I like downloading from here because I know mods etc. have been vetted for dodgy stuff.

As an uploader, it is a pain getting some of the requirements and I admit that I'd probably upload more if they weren't there, but I can also see how they're there to make it easier for downloaders.

More or less what I was swinging by to say. Go both to get a slightly wider audience.