LAPL makes it cheaper to GET the licence (saving approx 10hrs of navigation - which you can get later and upgrade to PPL, I have done it that way)
If you train on or later get a type rating for a TMG, then USING your licence will be cheaper, too.
Having a LAPL (with/without TMG) will allow you to get a SPL in approx. 1 day at many schools in Germany.
You get almost no credit, when going from SPL to LAPL/PPL.
(+LAPL/PPL are European licences which you can use across EASA countries)
ULs are certainly cheaper, with a second partner AND fuel, they will be overloaded (that is before holiday bags!), unless the total weight of both people is below 125 KG (and you are fine with toothbrush and towel)
Mind you, UL flying does not keep you current for the LAPL.
SEP flying does keep you current for SPL (12 hours in the preceding 24 months)
All depends, what are your intenions (aka mission profile) and what is the budgetary constraint...
If you rent, check out availability in the regions you want to rent.
In my case, I wasn't sure how much/long I would like flying, but wanted a solid basis from which to add. Hence LAPL as starting point.
After doing +/- 50hrs of fun/self-flying with rentals post exam, I decided to go to PPL for radio nav fitness and later night VFR...
Anything else to be decided as I go along.
Good luck and success