If the 12F675 does what you want then just stick with it, it's fine. If you're giving up on it due to the issues you're having programming it think again, you'll have the same problem with the next chip.

Why you'd want to use the 12C508 is beyond me, at the very least go with the 12F508 but nah, why? I mean, OK, if you're designing a product and building thousands then buy the cheapest you can find, if you build one then just use what you have or what you want to play with. I just did a little protoboard project with a 12F675.

If you really want to move "up" while sticking to the 8-pin package then perhaps the 12F1840 might be an interesting choice but for that you'll need to upgrade PBP.

/Henrik.