I changed my strategy from dividends to growth, so my yearly return is a bit low, about 10% - in the context of the almost 30% return the S&P 500 delivered in 2019 and that I consider my benchmark after my strategy switch to growth.
Best performer: Tesla, 250% 
At Freetrade, we’re eating our own dogfood, and this is my main account since 2018 (and will remain so, forever). I literally have most of my life savings here. I also have a legacy account elsewhere with 250% Tesla return to date. As many of you know, I’m a long-time investor and I personally think highly of the company and especially its CEO:
My conviction about Tesla doesn’t mean anyone should jump in or anything, please DYOR!
Worst performer: Royal Mail , -10% 
I thought I bought it at a good price around £2, but the company recently said it may fail to deliver on the transformation plan, with the primary goal to have 70% of its sales from parcels (due to the rise of ecommerce) by 2024, with an increasing proportion of the revenue from overseas. That is fine for me - I’ll keep the stock for the dividends and because I appreciate an ambitious and hard-to-achieve plan, which is better than having a realistic but mediocre goal.
Thanks for the thread, @anon810895!