Some good Vietnamese, Thai and Khmer foods can be found around town and at the border market.
If looking to sample local foods, a good place to start in Aranyaprathet town is the day market on Ratuthit Road, where vendors dish out noodle soup, Vietnamese style banh mi sandwiches with peppered pork sausage (famous in the area), and fresh fruit.
Similar foods are readily available in the roofed "tunnel" section of the border market along with fried crickets on the one extreme and French fries at Border's cafe on the other. Border's also sells excellent coffee, fruit shakes and decent American breakfasts if needing a wake up before hitting the border.
Back in town, a handful of local restaurants can be found just east of the train and bus stations on Route 3. We had some delicious Vietnamese style kway chob noodle soup (70 baht) with local moo yor sausage along with fresh spring rolls (50 baht) served with tons of greens at a Vietnamese restaurant on the south side of the road. The menu comes in mini Kodak photo albums so you can see pictures of each dish before deciding. There's no English sign -- look for red Thai script on a large green sign next to a local roast duck joint, which also looks to be worth a try. Across the street we saw a couple of steak/coffee houses with air-con seating that are probably good bets if looking for a more Western-style meal.
The cafe at Market Motel serves up fresh coffee, beer and Western breakfasts along with basic Thai food in a relaxed open-air setting, making this a safe bet for those wanting a more traveller oriented atmosphere.
Aran Mermaid Hotel has a pricier air-con restaurant that serves wine and cocktails to go with watered down Thai food to fit Western tastes and Western basics like burgers and spaghetti.
If it's authentic Thai you're looking for, a handful of local joints around town have small English menus. We had some tasty cashew nut with chicken and Isaan-style mushroom soup at Top Tin Tong restaurant just south of the clock tower at the corner of Ratuthit Road. There's no English sign, but the blue Thai script on a white sign smack at the corner is tough to miss.