I, too, have a "mid-2010" MacBook Pro 13".
And my main OS on it is still Snow Leopard 10.6.8.
Actually, it still runs fine.
I also have a second partition on the internal drive, with a copy of 10.8.5 on it.
That runs fine, too -- however, the original 10.6.8 runs so well, that I've never bothered to update it.
I now have an SSD that I need to swap out with the original 250gb HDD. I'm pondering whether to go with 10.8 as my main OS or not.
I've been experimenting with Mavericks on my 2012 Mac Mini. Like others, I have noticed some quirkiness about it, such as slow loading of apps, etc. My -guess- is that this is due to the completely-changed way in which Mavericks handles installed memory (it "loads it all" at startup, and then does some kind of "memory compression" as it shuffles RAM around). I actually think "the old way" worked better.
My advice:
If your installed copy of 10.6.8 still runs smoothly and quickly, and you don't absolutely need to upgrade, you can keep using 10.6.8 for a while longer.
or
If you'd like to update, I'd suggest going to OS 10.8 (Mountain Lion) for now.
or
If you want to try going all the way to Mavericks, MAKE SURE you create a bootable clone of your existing OS on an external drive. You might find yourself unsatisfied with the results...