I've not tried the Tenga so can't really compare, but my Fleshjack Ice (or 'Icejack') is by far the best cock-stimulating sex toy I've ever used.
I have the Speed Bump insert and it's deliciously tight, especially after a good few pumps when you've built the suction up!
Plenty of lube is a must though. You can also use it with another guy, although I've found it makes a rather comical slightly off-putting noise if you do!
The Ice version is really hot to watch though because you can still see your cock/the guy using it's cock. Plus it's also rather intense if you use it while you're being fucked.