GoOpti

I'm going to be using GoOpti for airport transfer in Ljubliana and to Lake Bled a few days later, at end of August. If you're not travelling till after that, I'll post my impressions here.

Last September we (3 adults) used GoOpti for a daytrip from Trieste to Piran and return. Their online platform was easy to use. They picked us up in Trieste at door to our hotel and in Piran at a designated point. Seems like there are options for private and/or shared transfers. Ours was private both ways and I thought the price was reasonable. Drivers were prompt and professional. I think it is a good option and I would use them again.

I haven't used either company, just read comments from some of their clients on this forum--overwhelmingly happy clients, from what I can tell. I wouldn't hesitate to use GoOpti or DayTrip if I needed that type of service myself and was willing to pay for it, but I'd expect GoOpti to be less expensive, because it seems to serve a limited geographic area, providing the service itself. DayTrip looks like a third-party operation that connects travelers to service providers all over Europe (and maybe beyond?). DayTrip has to make some money off the deal, somehow, which I figure means the clent pays more.

I think Ljubojana to Lake Bled is a special case. It's a very short trip, and I'm sure it would be simple to find a local taxi very happy to make that run.

I used GoOpti for a trip from Graz Austria to Ljubliana a few years ago
No complaints.