I did some research on most of these platforms and here are my comments.
Bondora
Edit: The loans are all with the platform owner. Negative returns realized by Jørgen suggest there is no buyback of defaulted loans.
Crowdestate
Cracks already showing. Some projects significantly delayed, therefore promised returns will not be realized in full. At least one developer already bankrupt (see their Marketplace)
Crowdestor
Very few projects, means high exposure to individual loans. Risky.
Envestio
20%+ returns is just fishy. Most projects are “Tiers” of existing loans. This leads me to believe they are just refinancing the previous loans for as long as they can get away with it. Many previous projects were crypto mining farms based on GPUs. To anybody in the know it is clear that GPU mining is not profitable at current prices. No chance this will get repaid.
FastInvest
Only two, unspecified, loan originators. Too little transparency, too little diversification. No go.
Grupeer
As I write this, only 16 loans available with 3 originators. Too little diversification.
Mintos
230’000 available loans with 50+ originators, good transparency.
Robocash
Looks like all loans are with the platform owner (Zaymer=Robocash). No diversification.
Swaper
All loans owned by one financial entity. No diversification.
Twino
One of the oldest platforms (2009). Apparently reliable, offers buyback guarantee. I can’t find any info about loan originators or the loans available (lack of transparency).
Out of all these platforms, I only found Mintos suitable to trust with some play money. I’ve been with them for 4 months and it’s been going fine (support, withdrawals etc.), but the real return is closer to 11.5%. Here’s my referall link if anybody is interested: www.mintos.com/en/ref/L7M93R . Let’s see if I can get my 19000+ EUR in referrals!!!