Hi GTD184,
I'm not going to make your decision any easier

The Tiguan is a beautiful car full stop. I have an SEL and I'm really pleased with it but while it had to have some snags fixed, I have driven the the R-Line for a few day as a replacement.
The R-Line is a fabulous car and the main differences I noticed are:
It has a "tauter" ride that the SEL. I tried the R-Line with Sport setting as well and its definitely more chuck-able than the SEL (but that could be me)
It has a great body kit, so if you want something more conservative, the SEL is for you (but both will get noticed)
It has bigger diamond cut alloys with lower tyres.
Thigh support is great in the SEL.
Leather standard on R-Line.
No idea why DCC isn't an option on R-Line.
I'm sure others will have an opinion.