And when the weakest, lowest level character of one class is tougher than the strongest, highest level character of another class, and the first player wants to play one and the second player wants to play the other, which player voluntarily gives in?
[rant] With D&D, the characters are at least in the same ballpark, and in my personal experience a lot closer to balanced than you seem to find them. Note that on these boards, we do sometimes get "X is too powerful" or "X got the shaft", but what is interesting is that sometimes it is the same class that is thought to be too powerful or too weak by different groups. I don't think that is as common with Rifts. With Rifts, the classes are not even close to balanced. Looking at just the Rifts core book, a rogue scientist and Juicer don't belong in the same party. And it gets worse with the supplements (and these are official supplements, so there is no one else to blame). The GM has to ban an astonishing number of the classes to have anything like a balanced game. I would not be surprised to hear of people accidentally creating unbalanced Rifts characters (either too weak or too strong). With D&D, classes are more often banned for flavour reasons, but I have never played in a game where a core class was banned for being too powerful or too weak, nor (with ECL) in a game where a MM race was banned for being too weak or too powerful. Getting into oher books (especially some 3rd party publishers (although some 3rd party guys are models of balance, not all of them are)), there are sometimes classes (prestige classes would be the weak spot here) that come off as too weak or too strong. But interestingly enough, when this happens with a wotc class, wotc listens and responds. The Psion, which was too weak before, has been corrected in 3.5. The Duelist, which was too strong before, has been weakened in 3.5. There is even a book out now, called Unearthed Arcana, that gives a DM extra tools to tinker with the game if he thinks that a class is too weak or too strong in his or her campaign. Think of that. A tool to help the DM if he or she thinks his game is unbalanced. Rifts has never, ever, even tried corrected for balance, and it is not fair to place the entire burden of balance on a GM.
It would take a lot less energy for a GM to memorize the 3 corebooks of D&D from scratch, create an exciting D&D game world, and detail the major NPCS and plot lines for the pc's than to try to balance the classes of Rifts. In fact, it would be easier to make up a Rifts-like setting for a d20 game, using the d20 rules out there, than it would be to try to balance Rifts. And that means that you could get all the flavour of Rifts with balanced d20 rules, up to and including being able to play all the classes, something that one could never do in a Rifts campaign using Rifts rules.
Rifts is like a sopwith camel held together with chewing gum, and with a heavy weight on the right wing. Or better, like a leaky rowboat in the middle of an ocean that sprouts leaks almost faster than you can fix them (and you have to bail as you go),
D&D 3.5E is like a modern jet plane. It is sleek and balanced, and if it goes slightly off course is easily correctable with the touch of a clearly marked button. It is not only balanced, it is the most balanced roleplaying game ever created. And it allows the DM to spend more time with the fun aspects of the game (creating the plots, etc.) and less with the mechanical stuff. [/rant]