For the most part Orange Park is an good area. People who have lived in Orange Park all their lives refer to Fleming Island as were the "rich people" live. LOL.. NICER area, but more expensive.
As far as Jacksonville goes, Mandrain is nice, Southside is nice, Beaches nice, the UPPER Northside is nice, however the lower part of Northside, the area around Lem Turner Blvd is NOT NICE avoid that area. The Westside is so-so depends on where you live.. that pretty much goes for the rest of Jax that I did not mention. A word of advice though...the historic parts of Jax (Springfield, Riverside, Five Points) are nice but have a high burglary rate(there was a news report on it once).
But I know realtors will certainly steer you into the right direction within your budget.