I have cues with metal, ivory, and phenolic joint collars - as well as collarless joints. The first question was about collars, so I suggested only weight and esthetic effects. And so this thread developed....
The best joint, to me, is an ER Radial screw joint. Beats Uniloc. Geez, I was first made to hit with it with the shaft half-screwed in. Solid! With the shaft screwed through, Rock-Solid!!!
It reminded me of those extinct fragile wood screws that are very hard to repair. Wood to wood gives a very solid feel. The later versions came with ugly brass collars to compensate with the short balance point of the cue.
If it isn't so inconvenient to carry one of those long snooker cue cases, I would play with a jointless, one-piece solid wood cue. But the downside of it is the lack in manipulating the balance point.