>>932594Palomar. Easy to tie and probably the strongest. All you really need for tying on hooks, lures, swivels, etc.
For tying line to line (like leaders) I like the "Double Uni" or "Uni-Uni" knot because I can tie them well and smooth but I know lots of others like the FG.
And then if you need to tie a loop on line, the "Surgeon's Loop" is all you need. I will often tie Texas rigs and other leaders and do a Surgeon's Loop at the end so I can attach them to the main line with a snap swivel (because I'm lazy).