Since I got it for my birthday, I've been carrying a Gerber Bear Grylls Compact Scout (Yes go and laugh), and really enjoy it. It's so light and slim you really do forget it in your pocket, but it's of a useful size and has a solid lockback with no blade play at all. It's partially serrated, and while I'm not a fan of serrations, I'm warming up to them and quite like them on this handy little knife. Easy to sharpen and keeps its edge fairly well. They go for like $20 I think in the USA, have a look at them if you're interested. Some days I'll throw my opinel no. 9 in my bag, but this compact scout has been my main knife for a fair time now. The orange on the BG has rubbed off long ago, but I don't care
Otherwise get a SAK or an opinel no.6 or whatever. Both useful and cheap but of good quality