I've used a few riggers. My favourite for single seaters was the Udo Rumpf - with the lateral adjustment option. He pased away and nobody bought his tooling (even though it was offered pretty cheap).
For the Duo we've used the Cobra electric and now have the IMI electric.
The IMI is fantastic, and not very heavy. The battery lasts longer than the larger battery in the much heavier worm-drive Cobra.
I own a Cobra manually adjusted rigger, used it on LS4, LS6, ASW27 and G29. Like the Udo, I like the crank.
Have used the WingRigger, it's nice and light. The three-wheel setup is nice in most situations, but am not a fan of the gas strut type, especially rigging on uneven ground. The (original) plastic wheels can fail if used on heavy wings. Believe Mark changed that.
In the grass or dirt you need to adjust more than on paved surfaces.
Adjustment is also a bit of a hiccup with old the style (even JS3 mwent back to it) spars with a single pin and spar-end spiggots. At least with the Libelle (we had a WingRigger for that) you can see wht is misaligned and there is "the tool".
The Duo often needs a bit of a wiggle. Rigging aids don't wiggle well.
With any solo rigger, an alignment device (cam or pry bar type) is very handy.
The cam type that MM Fabrication has is perhaps the best. Cobra second best I've used.
Jim