Will both type cradle booster improve signal on phone, tablet, laptop?
No, neither of the two types of combined cell signal booster and phone holder can boost reception on all 3 devices at the same time. Both of them can only boost a single device at a time. A cradle booster only boosts signals for a device that is placed in the cradle. Connectivity for other devices can be improved by placing a phone in the cradle as a hotspot device. This will allow other devices such as tablets and laptops to benefit from the boosted signal if they are using that boosted in-cradle phone's hotspot. The phone must have hotspot capability to be used in this way.
Similarly, a mobile Internet hotspot (MiFi, JetPack, etc) could also be placed in the cradle.
If you need a cell phone signal booster that will boost signal for laptops and tablets as well as phones independently and simultaneously, a wireless in-vehicle cell phone signal booster is probably your best option.