Taking into consideration the 'long-term' results, the average slot machine offers higher profit than video poker. The reason is obvious: a poker is a game of skill, and market competition forces all types of casinos (online and land-based) to award winners of games of skill higher than games of luck. Most people are not skilled in playing casino games, so casino can afford high awards for those who have mastered hazard games, assuming that a profit will come from other players' mistakes.
I can show you how to get the maximum return out of a video poker machine, but you need to remember that the maximum return may still be less than 100%. Any theoretical return of a video poker machine that's less than 100% means the casino has an edge over you, and this takes place in slot machines, Baccarat, or Roulette. The difference is that the casino's edge in a video poker game may be (but is not always) comparatively small; in the vicinity of 1% or so. Even by making a lot of mistakes, the average player can reasonably achieve a long-term return of over 97% when playing a good video poker game. By 'good', I mean a game like full-pay Jacks or Better, which is widely available on the Internet. This version of video poker offers a return of 99.54% if the player uses the proper playing strategy. That translates into a casino edge of about 0.50% which is similar to the average Blackjack game and is undewhatly a lower edge than the average slot machine, which is typically 3-5% at best.
However, to effectively realize the total return of a video poker game one must, at one point or another, receive a Royal Flush and its cousin, the Straight Flush. These are rare; a Royal will come only once every 40,000 hands and a Straight Flush once every 9000 hands, on average. Because we're dealing with surprises in a random game, there's nothing to stop you from getting a Royal on your very first hand, but it's not particularly to happen. And the short-term lack of such hands alters the return you can expect when you play, say, 1000 hands of video poker, which is two or three hours of gaming. I do not want to get too involved with mathematics here, but the Royal Flush and Straight Flush add a total of 2.53% to the 99.54% return of the full-pay Jacks or Better video poker game that I mentioned earlier. Because it's not realistic to hit either a Royal or a Straight Flush during the course of 1000 hands of play, your return will likely be more in the area of 99.54% minus 2.53% or 97%. That translates into a 3% casino edge, which is not far removed from that of a good slot machine.
What is a 'good' slot machine? Well, I do not know, because they can not be measured like a video poker game. But, just for discussion purposes, let's say we can identify a slot machine that has a long-term return of 97% (a 3% casino edge) and it requires 3 quarters per spin. Typically, a quarter video poker game will require 5 quarters per hand and both slots and video poker games can usually be played at a rate of about 400 spins or hands per hour. You can easily see that playing 400 spins on a slot machine at $ .75 per spin means you'll be betting $ 300 per hour and playing 400 hands of video poker means you'll be betting $ 500 per hour. If the casino's edge, in the short-term, is 3% on each game, your expectation is to lose $ 12 per hour while playing the slot machine and $ 15 per hour when playing the video poker game, assuming you use the proper strategy.
Sure, if you're going to play on a regular basis, are willing to finance the inevitable losing sessions that are part and parcel of video poker and are willing to learn the proper playing strategy, then video poker is a better way to go, because your long-term results will likely be much better. But to many people, gaming is a form of relaxation or entertainment so I can not blame those who'd rather play a slot than a video poker game, especially if you have a spare $ 20 that you want to gamble with. Throw in the fact that many slot machines - primarily those without a progressive jackpot - pay proportionately; that is, the return for one quarter played is one-third of the return for three quarters played, your $ 20 may get you several hours of entertainment. But unlike going to a movie, play or sporting event, this is entertainment that could see you walking away with a profit.