Tableau is great but is also pricey. I like that it can be on-prem which is a nice feature most saas players can't match. They have drivers for tons of sources.

Zoomdata is a good alternative, but pricey and not mature enough I feel.

PowerBI is getting surprisingly good, and if you're a Microsoft or R shop it can be a really nice fit for the price. I've thrown a few 50GB+ CSVs at it. It's basically Excel on steroids. If you're dealing with some data stores (like mongo, elasticsearch) then PowerBI isn't viable natively.

Interesting to note that zoomdata and tableau use spark under the covers iirc.