These are my favourites in no particular order.
1. Opinel Classic No 8 in Inox SS - Inexpensive, easy to clean, excellent for food prep, my overseas travelling folder.
2. Benchmade Mini Griptilian MDP in 154CM - My backup folder. Light, rides well in pocket.
3. Spyderco PM2 in S30V - Pointy, full flat grind, able to use full-length of the blade due to lack of a thumstud, easy to clean and ergonomic handle.
4. RHK XM-18 3.5" S35Vn Spanto -Heavy duty flipper, ergonomic handle although thick and heavy, easy to clean, rides well in the pocket, excellent fit and finish.
5. CRK Umnumzaan S35Vn drop point - Pointy, ergonomic, easy to clean and maintain, heavy duty with excellent fit and finish, rides well in pocket.
6. CRK 21 Large Sebenza S35Vn drop point - pointy, ergonomic, easy to clean and maintain, heavy duty with excellent fit and finish best edc folder for me.
There are a tonne of folders available with a budget of $500. Everyone needs are different therefore to get the ideal folder, trying them out is the way to go. I myself during the earlier years have tried many folders from Benchmade, Kershaw, Strider, Dpx Gear, Lionsteel, Spyderco, Zt etc basically what I can get at my local dealer. It did get a bit expensive at one point. Its when I bought the Umnumzaan in 2014 that I knew I am getting to my ideal folder. A month after getting that folder, I had the chance to get the Sebenza and I am glad I did. It was the folder of choice for me.