I'm using Algolia and SolR in production for an e-commerce website.
You're right about what you say on Algolia. It's fast (really) and has a lot of powerful features.
You have a complete dashboard to manage your search engine.
For SolR, it's ok but it's also a black box. You can fine tune your search engine, but it exhibits poor performance for semantic searches (I tested it).
If you have to make a choice, it depends on a lot of things.
With Algolia, there are no servers to manage, easy configuration and integration. It's fast with 20 millions records for me (less than 15ms per search).
With SolR, you can customise a little bit more. But it's a lot of work. If I had to make a choice, it would be more between Algolia and ElasticSearch. SolR is losing velocity; it's hard to imagine it growing again in the next few years.
As a resume, if you want to be fast and efficient, choose Algolia. If you want to dive deep into a search engine architecture and you have a lot of time (count it in months), you can try ElasticSearch.
I hope that I was helpful with my answer, ask me if you have more questions.