I have the Evenflo Triumph DLX and I love it as do both of my kids. The newest version actually goes up to 50 pounds instead of 40. It's rated as highly as the Britax, safety wise, and it's about $100 cheaper. I've been so pleased with it, that i'm thinking of getting another since I have two kids now. Definitely read the manual though, because there are features that can be frustrating if you don't know how to work them, like the harness tightening and stuff like that. It's really easy if you know how to do it, but I read many reviews where people were complaining about certain features being difficult, and it was obvious they didn't read the directions!
We have one of the booster seats with a tray that straps on to a regular chair. Ours is the first years, but now there are so many out, I don't know what I'd choose. I love that it turns into a booster that pushes up to the table, so it's one less thing to buy, and I also love that I don't have a big high chair in my eating area. I don't love that I lost the use of a dining chair. It's inconvenient when people come over and I have to unhook it so we can sit down...