I don't know what to do. But in short:
1) I've already "publicized" my Blogger blog on places, so doing the same with Tumblr would be too daunting a task.
2) Tumblr has lovely themes. So does Blogger. No edge on that.
3) Both aren't really Search Engine Optimized
4) Tumblr's interface is a little cluttered (but nice in another way) - either way, I think the advantage still goes to Tumblr
5) I tried posting with Tumblr, and the linebreaks are awful - I can't distinguish between one paragraph and another!
6) Images are restricted to 500pixels at max. That's not the case in Blogger (although Blogger has it's own host of issues)
7) Blogger posts can be written from many places - considering it's old, established, and well-known. That's not the case yet with Tumblr.
8) I really really like Tumblr, and I think it's got a lot of potential - but what do you do when you don't have a basic comment system up and running on each post you make over there? Inserting HTML code should NOT be necessary :/
So I ended up switching back to Blogspot. Yeah - not the best interface and all (and I know my blog is uglyyyyyyyyyyyyy!) but - atleast it works!