When making a new game it can be very easy to get lost in all the fun stuff that you're designing. Giving PCs powers, or setting up intricate ways for players to make their character unique and stand out can seem like very good things to have, but they do come at a price: character creation time. Character Creation Time (or CCT for this post) is something that a lot of us take for granted, but how many of us really think about what it means, and how it can shift the play experience of a player?
Long vs. Short
The core debate when it comes to CCT is do you want to have a long CCT or a short one? A long CCT will likely let players really customize their characters and make them unique and stand out. They can pull abilities and powers from a number of places, and really work things to get the person they want. GURPS is probably a great example of a Long CCT System. A short CCT on the other hand will likely give less chance to make your character unique or stand out, and your choices are a lot more streamlined. Instead of doing detail picks, you make category picks and reap benefits that cover a larger area in game. However, it would be a mistake to think this is the only thing to consider.
Time To Play
One thing you want to keep in mind when working on your game's CCT is how long it takes a group of people to get into the game and play. If it takes 1-2 hours to make a character then you are looking at having to give up a session to make characters for your group, or you have to make them before session. This can be a problem in some groups where people just want to jump in and play, because the CCT for your system is actually a hindrance to pick up and play sessions.
Some systems circumvent this by having CCT also used for things such as modifying the setting, laying down some challenges for the campaign, or establishing pre-existing connections between the PCs. These can be fun things to do, but is also a clear sign that the game is focused on being used for campaigns more than say an evening of fun. There is nothing inherently wrong with that, but it's important to know that is where your focus is.
Time to Play is also something to consider when you are determining how lethal your system is. If your game is designed to kill players dead, and be right quick about it, then you are going to want a shorter CCT. Why? Because it is really going to suck when a player dies (like your system is made to do) and then has to spend the rest of the night making a new character while out of the game. Sure, this may be fun for some people, but wouldn't you rather be playing with your friends than doing intricate math on a new character - and then interrupting the GM to check it - while everyone else continues the story?
While not a hard rule, a general rule to follow is this: The higher your system lethality, the lower you want your CCT to be. Now, exceptions can be made for systems that have ways to circumvent death (i.e. Fate Ranks in Dark Heresy/Rogue Trader/Deathwatch), but that is because "death" in those cases doesn't mean "make a new character." Also, on the inverse this means that the harder it is for your system to permanently kill a PC, the longer your CCT can be. Within reason, anyhow.
Introducing New Players
The last thing you want to consider with CCT is how able it is to introduce a new player to the system. Systems like GURPS with longer CCTs don't do well at bringing in new people all the time, because they need help with the long CCT and can get confused in the process. In those cases, you're better off making a character for the new person and getting them in on the 'fun' quickly. On the other hand, a short CCT can work great for teaching a new character the system because it can help show them the pieces that will be going together in actual game. Someone who knows they bought a "Swords skill of 3" will have an easier time understanding what "Roll swords and agility" means than someone just given a sheet with numbers on it.
Which Is Better?
Like with all design questions, there is no real right answer here. Some games do better with a long CCT because that is what they need. This is true in a lot of super hero RPGs where character uniqueness can be very important. Other games need a shorter CCT, either because they're very lethal systems, or because the game is meant to be capable of 'pick up and play' type sessions.
However, you need to know what type of game you are making, and how long of a CCT is best for that type of game. You don't want building a new character to be a chore in a game with high lethality after all. Nor do you want everyone to look the exact same, and be able to do all the same things, in a system meant for long term play. Find the right path, just be sure you know where it is.