When it comes to accessibility, Online Blackjack wins over Live Blackjack. There are a few reasons why online blackjack is by far the most accessible form of the game: With no time restriction on moves or hands, you may determine your own pace. If you need a seat at any time of day, you can always find one.
So while the odds are ever so slightly better in live blackjack compared to online blackjack, it's really one of those things you'll get a feel for by practicing. Try both versions of the game, and see which one suits your playing style and risk profile.