Cast iron skillets are great for frying fish, meat, eggs etc. If you're after a rather large pan and want to be able to cook sauces etc in it, I personally wouldn't recommend bare cast iron for two reasons: 1) a large cast iron pan will be heavy as hell, and 2) cast iron doesn't like being used with acidic sauces (tomato-based pasta sauces, vinegar in the water for poaching eggs, etc.
Non-stick has problems for various reasons, as others have mentioned (scratching, killing budgies, etc).
So depending on exactly what you want to do with it, the ideal would probably be:
1) A cast iron pan of whatever size you need (not too huge). Lodge make reasonably good ones, though way overpriced in NZ. I prefer the old one I got from mum's place, though I did spend a bit of time cleaning it up and seasoning it before use. Once seasoned, this will be awesome for any frying you'll do. Make sure it has a metal handle so it can go in the oven (I roast chickens in mine).
2) a 3 or 5-ply (aluminium core) large stainless saute pan with high sides for making sauces etc. I got a good deal on an end-of-line 30cm Scanpan Fusion one for about $100 (pictured below) which I absolutely love, but there are plenty of other options both cheaper and much more expensive. I use it for poaching eggs, making pasta sauces and curries, cooking veges, all that kind of stuff. It goes in the oven too.
It is not as non-stick as a good cast iron pan, so not so great for cooking fish etc. That said, as long as you let it heat up a bit before adding the food (flick some water in and it should roll around like mercury), and use a bit of oil I find that it's pretty good when I need to do larger batches than my cast iron can handle.