I'd day The first three riders, didn't they need wind to power the transformation?
Since most of the heisi have belts compared to having them installed as cyborgs, the only bad thing is the fact they can lose the transformation device
In terms of Heisi my scale is
Kuuga

erfect, he literally can summon it any time and doesn't have to worry about having it nocked out of his hands
Agito:Same for Kuga
Ryuki:Well aside from needing a reflective surface it's not to bad as you just need to insert the deck
Fai: this is the start of the carry around belts, the bad is he has to lug it around, then insert a cell phone after making a call
Blade:Not to bad, a buckler and a card
Hibiki: Pretty good, he has to carry around a little whistle
Kabuto:Have to lug a belt around(or other various devices) and then wait for a zecter
Den-o:Lugging around the belt and either needing a host(imagin) or the sword to fight
Kiva:similar to Kabuto he has to wait for kivat
Decade:The best by definition as its a buckler and can transform to any rider or just use the abilites in default
W:The double driver is terrible as you need two people to transform and if one can't you're screwed
OOOs: Eh, it needs 3 coins or its screwed
Fourze:It's bulky, the start up is long, you need at least four switches to activate
Wizard:Not to bad the driver always seems to be on haruto, just need a transforming ring
Gaim:Again not bad, a buckle and lock seed, and if your in helheim you should be fine as there's an abundant source of lock seeds
Please don't think I hate a series if I said a driver sucked, I loved series like W or Fourze but honestly the Drivers can be a little impratical