I would avoid slime inner tubes or adding slime to inner tubes for two reasons.
They only work with small punctures, you can end up with things like thorns, nails and bits of glass stuck in your tyres and not even know about it, which won't help you in the grip department. Also they add a load of extra weight to your wheels which is never a good thing on a bike. Unless you are a cheating ebiker. Regardless of what you use a bike for, the last thing you want is extra weight on any rotating part.
Had a few negative experiences with slime when I was commuting by bike but did invest in a set of Kevlar belted tyres for my road bike and it made a massive difference to my puncture rate more than justifying their extra cost.
For puncture protection I use these on my leisure bike:
and something like these on my road bike (they've update the range lately, so cannot find the exact one I have fitted):
The Schwalbe's are amazing - the blue layer is thick enough to take a drawing pin and not let it through. It hard wearing and I've not had a puncture on these... but they are hard to fit and would be difficult to remove on the side of the road.
The continentals are good, the vectran layer helps reduce punctures, but you still get a few - I reckon less than one per 1000 miles ridden.