I really like Dave Whitlock's Zap-A-Gap method of attaching either the leader directly or a mono loop. You basically thread the mono into the tip of the line and glue it permantly. The line/leader junction is perfectly smooth and will run in/out of the guides easily. I find this important with our close-quarters style of fishing as the end of the line passes the tiptop quite frequently. Just google it or look on Flyfisherman Magazine's website. I have found this to be a very strong attachment.