Outdoors? Harsh weather... Either aluminum or carbon. Unless you want an ultralight paint only bike, don't buy an old steel bike. Really any aluminum bike made in the last 20 years will do the trick. I'm not sure what sort of riding you do so can't really recommend a bike. I convert old aluminum and steel road bikes into cool things like I'm doing with my bike log down below (I hate the word blog, it sounds like something you do in the toilet like taking a bog).
I really would not recommend a steel bike if its going to be living outside but you should be able to find a decent high quality aluminum road bike in your size from a reputable brand which doesn't need all the perishables replaced for $500. My Trek cost me 300 beans it has less than 6000miles on it and 2 owners now. You just have to keep searching until you find something worthwhile. My Giant cost me $100 but the groupset on it did not.
My Trek had a full 6600 Ultegra groupset on it and its made out of SLR grade aluminium. That's my benchmark right there for value for money on a bike that needs nothing spent on it.
Last edited by 1500SLR; 04-17-18 at 06:12 AM.