I am not going to argue the merits of crimp vs wire nut or spike vs elliptical crimpers, what I will say is that in both wire nuts and crimp fittings, using the correct size splice for the wires being spliced is important.
I have crimp fittings for 22 AWG to #4 and I have crimpers for all those sizes. I also have wire nuts that were designed for use with two to four #22 wires up to four # 10 wires. Actually the twist on devices I have for #14 and above are generally called Scotch Locs and not wire nuts. Same principle and same rules regarding size.
I also have several "trailer splices", once again size is of the utmost importance.
Use the correct size and install according to the practices for the splice being used.
And finally, nothing is 100% foolproof.
