It really depends on what you want to spend. If I were replacing both on a limited budget, I'd make sure I purchased a good rest before a premium site.
As for drop aways, there are a lot of good choices out there. For me, I highly recommend the Limbdriver from Vaportrail. Its stupidly simply to setup and is easy to tune. No need to tie anything into a cable and worry about effecting letoff, holding weight, etc. If you are competent working on bows, you can have it setup and ready to shoot in 10-15 minutes.
I personally use Spot Hogg sights, though they are pretty pricey. I've had one on my hunting bow now for 4 years and don't ever see a need to change anytime soon. The sight will most likely outlast me. But again, for one of their mid to upper end sights, you're looking at 150 to 200 dollars.
If you can't spend that, I'd recommend looking into the Copper John line. Ruggedly built and bright pins. They have a pretty good following and have been around for some time.