Wow well it really depends. It depends on your experience level. If you have it dialed in then it isn't too hard to get fish to bite. But if your a newb, then its very hard. So asking which one bites better all depends on how much experience the person answering has.
Aggresiveness? I'd go summer steelhead, then spring chinook just because of water conditions. Chinook are easier to find, steelhead tend to move around a lot more.