It used to be that the odds on all the machines were brutally worse than the tables. But with the advent of 6-5, and even 1-1, payoffs on naturals, the gap has closed.
The traditional problem with blackjack machines has always been that, in the overwhelming majority of cases, the machines pay only even money for a natural 21, a rule that costs a whopping 2.3%. Why? One big reason was that they could get away with it, as the skill and knowledge levels of machine blackjack players tend to be well below that of table players. But there were also issues with mechanically issuing a 3-2 payoff, especially on the early machines with low denoms (a 3-2 payoff for a $1.25 bet is $1.875, for example). For the same reasons, machines were often devoid of other player-friendly rules, such as re-splitting pairs, but it's the even-money payoff that was the killer.
These days, you can find many more machines that pay 3-2 on naturals. When you find them, they're usually good gambling options. Although the casino usually has the edge and the machines play fast (typically a negative when it comes to conserving a gambling bankroll), you can often play them for much lower stakes than the tables -- usually $1 per hand.
To determine which machines are good, check the rules (often on the "Help" screen). Find the payoff for a natural and make sure it's 3-2. When it's not, you'll often see something like, "Naturals Pay 2-for-1." That may sound better, but the "for" instead of "to" means it pays even money (one 3-2 machine is the big one showing up all around town that features the voluptuous female dealers on the big screen).
And here's one more time the blackjack machines (even the bad ones) are good: when playing for drink comps in a bar. If the video poker is terrible -- say, 6/5 Bonus paying back 96.9% -- you're losing less money per hand playing $1 (or less) blackjack at about a 2.5% disadvantage than you are playing $1.25 in the VP game holding more than 3%.
