Seche Vite claims their top coat is the world's finest--and you know what? It just might be. I originally got it from my sister-in-law, who said it's the only top coat that works for Konad nail stamps (i.e., doesn't make them smear everywhere). I liked it so much I started using it all the time.
The brush is a good size, it doesn't smear my polish, dries super fast, and leaves a super glossy shine. It also has helped my nail polish stay on longer, even those cheaper polishes that don't normally last that long. With most top coats, the ends start to chip within a day or so for me. With this top coat, it's extended to 3 or 4 days. I'm serious! And I'm definitely not super careful with my nails.
One downside is the smell; it's super strong. If you're sensitive to that kind of thing, I recommend doing your nails near a fan or open window. Another slight problem is that when it does start to chip, it more peels away than chips. This means that if you start peeling one side, half or the whole layer of polish might come away with it. However, I've found that if you put on a thinner coat, that seems to help with this problem.
Cost: $9-$10 at most drugstores--about the same as an OPI polish. For me, it's worth it because I use it for every manicure.
Fast-drying: It really only takes a few seconds to dry, which is perfect for someone who always messes up her polish right after it's done! While you still should be careful afterward, I can attest that the oh-it's-dry-wait-no-it's-not smudges have decreased.
Long-lasting: My polish looks nicer for longer, even when the polish isn't that durable by itself.
Shiny: The resulting finish is super glossy and shiny.
Repeat offender: Love this! So far, it's the best top coat I've tried. It smells a little strong, but the result is totally worth it.